The Sacrament of Matrimony, or marriage, is a unique sacrament because it is the man and the woman that mutually administers the sacrament upon each other in the presence of a priest or deacon and other witnesses.
It is a sacred covenant, a public promise made by the husband and the wife to be true to each other until death parts them. In order for a marriage to be valid, the couple must be entering into the covenant out of their own free will, without fear or coercion. They are also asked to honour and be true to each other for the rest of their lives, as well as to accept children lovingly from God and bring them up according to the law of Christ and His Church.
No. Many of us will be called to holiness by entering into the sacrament of marriage, but not all Christians are called to this vocation. If you are in a serious relationship and would like to learn more about marriage preparation, please visit: http://rcav.org/m-prep/
A Catholic may marry a non-Catholic Christian or a person from another religion, but he/she would need to seek Church approval before the wedding by way of a dispensation.
A dispensation in Catholic canon law is an exemption from Church law. The authority competent to issue a dispensation is the local bishop or the Apostolic See.