Hi!
If you already have a theater room, you may just want to consider going the stereo route in here. A pair of JBL 7-series monitors would provide every seat with top quality sound, and would not require a preamp or receiver, you could just plug them right in to the TV. Anchoring a shelf through to the masonry would not be a problem, and then you can always remove the shelf and repaint!
If your heart is set on surround sound, then definitely talk with Dawn, above! I have a set of Triad Bronze Inwalls from her and they provide good sound with a clean installation.