Baptism (into the RCC) may be administered by any lay person whose intention is valid, Catholic or not, who uses water and baptizes "in the Name of the Father and of the Son and of the Holy Ghost." This is often done in hospitals in the absence of a priest when a patient (usually an infant) is in imminent danger of death.
You do NOT have to attend Mass or attend the Sacraments to "be saved" or, as we would term it, to go to heaven. If you ARE a Roman Catholic, you are required to attend Mass on Sundays and Holy Days of Obligation (here Christmas, the Feast of the Immaculate Conception, the Feast of the Assumption, Holy Thursday which is trending optional, the Feast of All Saints and the Feast of the Presentation) under pain of sin. If you are not Catholic, I cannot imagine that you would feel bound by the commandment of the Roman Catholic Church that you attend those Masses or that you confess your sins at the prescribed time annually or receive the Eucharist at least once a year.
Confession is TO a priest who stands in persona Christi and is authorized by the Christ through the pope through the power of the keys. Absolution is FROM the priest under the same authority. The Eucharist can ONLY be confected by a validly ordained priest (ordained in thesacrament of Holy Orders) because only he may transubstantiate the mere bread and wine into the actual Body and Blood of Jesus Christ under the continued appearance of bread and wine.
The husband and wife are the ministers of the sacrament of marriage. The priest is merely the Church's official witness. If a man and a woman who are eligible to marry do so before a justice of the peace or before a Protestant minister, a rabbi or whatever, they marry. If they are alone on a desert isle, they marry but are expected to regularize the marriage when first able to do so.