If at all possible, I'd suggest that you try to be slightly higher than the surface of the stage.
That way you're not shooting up people's noses/ skirts / whatever, and you get to see people's feet - dancers, especially, like that.
For an amateur group not to have a dress rehearsal with makeup and scenery is very curious. It doesn't bode well for the opening night!
Where possible, I like to be able to wander around a lot, giving me all sorts of options for close-up and wide shots. Some companies are quite happy with this (they'd better get used to dealing with distractions because audiences don't sit stock-still), some are less so (don't put them off, especially the kids - they're having a hard enough time as it is).
My photos live at http://www.stagepics.co.uk and http://www.flickr.com …ctions/72157605174789525/ - feel free to look at them and decide whether to place any credence in my remarks.