Mark - in an ideal world, this is what I'd do:
1) get to the rehersal and scope out the best locations/seats to shoot from; have a back-up location if the prime spot is unavailable.
2) take some test shots to fine tune my slected manual settings and diecide the best spot/angle/position from which to shoot.
3) use my 2.8, 70-200mm for flexibility and not let my shutter speed drop below 1/200th but watch the ISO if flash not available.
4) double check I have everything backed up - extra lens, batteries etc.
5) stay awake for the whole shoot to get that 'wow' shot or the model falling off the stage!
Good luck buddy!