1. Difference between first three commandments and the next seven
The first three commandments teach us to love God, the Supreme Good and Final End of the human person and of all created beings, who is infinitely worthy of our love. The remaining seven are directed to the good of our neighbor (and our personal good); we are asked to love our neighbor out of love for God, our Creator.
In the New Testament, the supreme precept of loving God and the second, similar to the first, of loving our neighbor for God, summarize all the commandments of the Decalogue (cf. Mt 22:36-40; Catechism 2196).
2. Meaning and scope of the fourth commandment
The fourth commandment is addressed expressly to children in their relationship with their parents. It also applies to ties of kinship with other members of one's extended family. Finally, it encompasses the duties of pupils to teachers, of subordinates to leaders, of citizens to their country, etc. This commandment also implies and presupposes the duties of parents and of anyone exercising authority over others (cf. Catechism 2199).
a) The family : The fourth commandment refers primarily to the relationship within the family between parents and children. “In creating man and woman, God instituted the human family and endowed it with its fundamental constitution" (Catechism 2203) “A man and a woman united in marriage, together with their children, form a family" (Catechism 2202). “The Christian family is a communion of persons, a sign and image of the communion of the Father and the Son in the Holy Spirit" (Catechism 2205).
b) Family and society : “The family is the original cell of social life . It is the natural society in which husband and wife are called to give themselves in love and in the gift of life. Authority, stability, and a life of relationships within the family constitute the foundations for freedom, security, and fraternity within society … Family life is an initiation into life in society" (Catechism 2207). “The family should live in such a way that its members learn to care and take responsibility for the young, the old, the sick, the handicapped, and the poor" (Catechism 2208). “The fourth commandment illuminates other relationships in society "(Catechism 2212). 
Society has the grave duty to support and strengthen marriage and the family, to recognize their true nature, to foster and protect them, and to safeguard public morality (cf. Catechism 2210).  The Holy Family is the model of every family—a model of love and service, of obedience and authority.
3. Duties of children to their parents
Children have to respect and honor their parents, trying to give them joy, praying for them and appreciating their sacrifice. Every good Christian should find these duties a “most sweet" precept.
Divine paternity is the source of human paternity (cf. Eph 3:14); this is the foundation of the honor owed to parents (cf. Catechism 2214). “Respect for parents (filial piety ) derives from gratitude toward those who, by the gift of life, their love and their word, have brought their children into the world and enabled them to grow in stature, wisdom, and grace. 'With all your heart honor your father, and do not forget the birth pangs of your mother. Remember that through your parents you were born; what can you give back to them that equals their gift to you?' (Sir 7:27-28)" (Catechism 2215).
Respect for parents is shown by docility and obedience. Children, obey your parents in everything, for this pleases the Lord (Col 3:20). As long as they are subject to their parents, children should obey them in what concerns their own good and that of the family. This obligation ends when children leave home, but the respect owed parents never ends (cf. Catechism 2216-2217).
“The fourth commandment reminds grown children of their responsibilities toward their parents . As much as they can, they must give them material and moral support in old age and in times of illness, loneliness, or distress" (Catechism 2218).
If parents order them to do something contrary to the law of God, children are obliged to give God's will priority over the desires of their parents, always keeping in mind the words of Scripture: We must obey God rather than men (Acts 5:29). God is more a Father than our parents; all paternity comes from him (cf. Eph 3:15).
4. Duties of parents
Parents have the duty to receive the children God sends them gratefully, as a real blessing and sign of confidence. Besides caring for their material needs, they have the serious responsibility of giving them a solid human and Christian education. The role of parents in forming children is so important that, were it to be lacking, it would be hard to make up for it.  The parents' right and duty to educate their children is irreplaceable and inalienable. 
Parents have the responsibility of creating a home built on love, pardon, respect, faithfulness and disinterested service. The home is the appropriate place for forming virtues. Parents, through their example and word, should teach their children to live a simple, sincere and joyful life of piety, and transmit to them the fullness of Catholic teaching; they need to encourage them to carry out a generous struggle to live up to the requirements of God's law and of each one's personal vocation to holiness. Fathers, do not provoke your children to anger but bring them up in the discipline and instruction of the Lord (Eph 6:4) Parents must not neglect this responsibility, leaving the education of their children to other people or institutions, although they can, and sometimes should, count on the help of those they have confidence in (cf. Catechism 2222-2226).
Parents need to know how to correct because what son is there whom his father does not discipline? (Heb 12:7); they need to always keep in mind the Apostle's advice: Fathers, do not provoke your children, lest they become discouraged (Col 3:21).
a) Parents need to truly respect and love their children's freedom, teaching them to use it well, responsibly.  Their own example is fundamental here.
b) In dealing with their children, parents need to combine affection and firmness, vigilance and patience. It is important for them to “make friends" with their children, earning their trust and keeping it.
c) To succeed in the task of bringing up children, the supernatural means should be given priority over the human means, although these too are important and indispensable.
“As those first responsible for the education of their children, parents have the right to choose a school for them which corresponds to their own convictions. This right is fundamental. As far as possible, parents have the duty of choosing the schools that will best help them in their task as Christian educators (cf. Gravissimum educationis, 6). Public authorities have the duty of guaranteeing this parental right and of ensuring the concrete conditions of its exercise" (Catechism 2229).
“Family ties are important but not absolute. Just as the child grows to maturity and human and spiritual autonomy, so his unique vocation which comes from God asserts itself more clearly and forcefully. Parents should respect this call and encourage their children to follow it. They must be convinced that the first vocation of the Christian is to follow Jesus : 'He who loves father and mother more than me is not worthy of me; and he who loves son or daughter more than me is not worthy of me' (Mt 10:37)" (Catechism 2232).  The divine vocation of a child to undertake a specific apostolic mission is truly a gift from God to the family. Parents need to respect the mystery of their child's call, even if they do not understand it. Prayer strengthens this respect for freedom and the readiness to accept God's intervention. Thus parents will avoid being overly protective and controlling of their children, a “possessive" way of acting that does not foster their human and spiritual development.
5. Duties regarding those who govern the Church
Catholics need to have “a true filial spirit toward the Church" (Catechism 2040). This spirit is to be shown toward those who govern the Church.
The faithful “with ready Christian obedience … should accept whatever their sacred pastors, as representatives of Christ, decree in their role as teachers and rulers in the Church … Nor should they omit to pray to God for those placed over them, who keep watch as having to render an account of their souls, so that they may render this account with joy and not with grief (cf. Heb 13:17)." 
This filial spirit is shown above all by faithful adherence to and union with the Pope, visible head of the Church and Vicar of Christ on earth, and with the bishops in communion with the Pope.
Catholics know that, after God and our Mother the Most Holy Virgin, the Holy Father comes next in the hierarchy of love and authority. 
6. Duties toward the civil authority
“God's fourth commandment also enjoins us to honor all who for our good have received authority in society from God. It clarifies the duties of those who exercise authority as well as those who benefit from it" (Catechism 2234).  The duties of the latter include:
a) respecting just laws and legitimate mandates of authority;
b) exercising their rights as citizens and carrying out their duties;
c) intervening in a responsible way in social and political life.
“The choice of government and the method of selecting leaders is left to the free will of citizens."  Responsibility for the common good makes exercising the right to vote a moral duty (cf. Catechism 2240). It is not lawful to support anyone whose program for society is opposed to Christian teaching and as such contrary to the common good and to the real dignity of man.
“The citizen is obliged in conscience not to follow the directives of civil authorities when they are contrary to the demands of the moral order, to the fundamental rights of persons or the teachings of the Gospel. Refusing obedience to civil authorities, when their demands are contrary to those of an upright conscience, finds its justification in the distinction between serving God and serving the political community. 'Render therefore to Caesar the things that are Caesar's, and to God the things that are God's' (Mt 22:21). 'We must obey God rather than men' (Acts 5:29)" (Catechism 2242).
7. Duties of civil authorities
The exercise of authority should facilitate the exercise of freedom and responsibility by all men and women. Those governing must be careful not to give the personal interest of certain individuals priority over the common good. 
“ Political authorities are obliged to respect the fundamental rights of the human person. They will dispense justice humanely by respecting the rights of everyone, especially of families and the disadvantaged. The political rights attached to citizenship … cannot be suspended by public authorities without legitimate and proportionate reasons" (Catechism 2237).
Catechism of the Catholic Church, 2196-2257.
Compendium of the Social Doctrine of the Church, 209-214; 221-254; 377-383; 393-411.
 Cf. Compendium of the Social Doctrine of the Church ,209-214;221-251.
 Cf. Ibid , 252-254.
 Cf. Vatican Council II, Declaration Gravissimum educationis, 3.
 Cf. John Paul II, Apost. exhort. Familiaris consortio , 22 November 1981, 36; Catechism 2221 and Compendium of the Social Doctrine of the Church , 239.
 “When they become adults, children have the right and duty to choose their profession and state of life " (Catechism 2230).
 “And, as we are consoled by the joy of finding Jesus—three days He was gone!—debating with the doctors of Israel (Lk 2:46), your soul and mine will be left deeply impressed by the duty to leave our home and family to serve our heavenly Father" (St Josemaria, Holy Rosary , 5th joyful mystery).
 Vatican Council II, Const. Lumen gentium, 37.
 St Josemaria, The Forge , 135.
 Cf. Compendium of the Social Doctrine of the Church, 377-383, 393-398, 410-411.
 Vatican Council II, Const. Gaudium et spes, 74. Cf. Catechism , 1901.
 Cf. John Paul II, Enc. Centesimus annus, 1 May 1991, 25. Cf. Catechism , 2236.