they also do rehearsals and life boat drills.
On the Magic they have a Navigators session where you ge to talk to some of the cast. They did mention their ship responsibilties, other than life boat stuff, they are entertainers only.
By the way, when we did the 3 peat on the Wonder added 80's nite to the schedule (4 day only). You could hear them rehearsing when walking thru Route 66.