Jax brings up several good points.
This is NOT a small home theatre and you most likely won't find what you are looking forat Best Buy. ...and Bose is not the answer. Trust us on this one. This is not simply bose bashing, but unless you drop big bux into their pro stuff, it ain't gonna work.
From what you describe, I envision a mixer (for the theatrical productions), several amps and speakers* and some training on how to get the most out of it. We use some thong like this at our church and, if possible, you might want to check out what some churches in your area use.
A pro might be a good bet.
BTW, I don't recall you mentioning a budget. That might help. It ain't gonna be cheap.
*perhaps some eq and reverb as well as some NICE wireless microphones.