Just recently my parish has changed where the altar servers sit and how they perform their function. For as many years as I remember the altar servers sat beside Father with one being on each side during the appropriate time. Now they sit way off to the side, out of the sanctuary area when not active in their duties. The other thing that happens now is the servers are never to pass between the altar and the tabernacle. Because where they sit is on the opposite side of the altar from where they serve, when they are needed they cross in front of the altar (stopping to bow in front of the altar) and then proceed on. …
The 2002 General Instruction of the Roman Missal basically says: genuflecting to the tabernacle during Mass is out, bowing to the altar is in. Some quotes from it:
“274. … If, however, the tabernacle with the Most Blessed Sacrament is present in the sanctuary, the priest, the deacon, and the other ministers genuflect when they approach the altar and when they depart from it, but not during the celebration of Mass itself.”
“275 … b. A bow of the body, that is to say a profound bow, is made to the altar;”
The 1984 Ceremonial of Bishops has: “72 A deep bow is made to the altar by all who enter the sanctuary (chancel), leave it, or pass before the altar.” (Ceremonial of Bishops, Liturgical Press, 1989, ISBN 0-8146-1818-9, page 37.)
It also talks about bowing to the bishop, and has on page 38: “77. … out of reverence for both, ministers should, as far as possible, avoid passing between the bishop and the altar.” It don’t think it has the same “avoid passing between the tabernacle and the altar” but it seems like a good idea.
Regarding seating, the GIRM has: “310. … The seat for the deacon should be placed near that of the celebrant. Seats for the other ministers are to be arranged so that they are clearly distinguishable from those for the clergy and so that the ministers are easily able to fulfill the function entrusted to them.”
But they should be in the sanctuary, from the GIRM:
“294. … The priest celebrant, the deacon, and the other ministers have places in the sanctuary. Seats for concelebrants should also be prepared there. If, however, their number is great, seats should be arranged in another part of the church, but near the altar.”
“188. In the procession to the altar, the acolyte may carry the cross, walking between two ministers with lighted candles. Upon reaching the altar, the acolyte places the cross upright near the altar so that it may serve as the altar cross; otherwise, he puts it in a worthy place. Then he takes his place in the sanctuary.” And in 195, about the beginning of Mass: “Then the lector takes his own place in the sanctuary with the other ministers.”