Some information that might help:
Good discussion of "acoustical" ceilings
here. (I contributed to the page, back in the day...)
An alternative to wire hangers for added isolation for a massive ceiling
here.
Some other thoughts:
• "Standard" ceiling tiles from a home improvement store typically do not offer a very high NRC. Make sure whatever you're buying has a minimum NRC rating of about 0.80-0.90. The ceiling tiles at home improvement stores are usually in the 0.55 range - IMO, not what you want for a home theater space.
• The non-bridging paint idea for the tiles is fine. However, my experience is that the acoustical properties will be degraded to a small degree. Not nearly as much as if a normal paint is used, but there will be a measurable decrease in absorption.
• If you do wind up painting the tiles, all the more reason to make sure they have a high NRC to start with.
• IMO, the drywall-backed tiles are preferred to the mineral fiber-backed tiles. The drywall provides more (relative) low frequency absorption when placed behind the tiles. Insulation behind the
entire arrangement is important, though (mineral fiber or otherwise). The drywall simply adds mass for isolation
and provides a diaphragmatic effect = doubly beneficial.