Often it is the altar server or the priest
The priest leading the celebration of Mass can be called Father [name]. Sometimes the priest is referred to by his position, pastor, but not usually during Mass.
The altar
In latin, the name's origin, Camila means: "helper of the priest/servant to the altar"
The 'mensa' is the top of the altar upon which the sacrifice of the Mass takes place.
That is called a paten
The altar is a sign of Jesus, as the bread and wine are consecrated to become Jesus on the altar. Thus it very special, contains a relic of a saint, and is consecrated by a Bishop. So we bow before it. When the priest enters and departs, he kisses the altar as a sign of reverence.
altar
Yes. The priest will state the child's name several times during the baptism. After the baptism ceremony the priest will also need the child's name for the blessing.
The number of celebrants, concelebrants or other assistants are immaterial. Mass is the name for all such events.
Roman Catholic AnswerEach Mass begins "In the name of the Father, and of the Son, and of the Holy Spirit".
Altar - as in a sacrificial altar.