Without question, this is a job for Mr. Zohn. PM Robert about this, solicit his advice and follow his instructions to the letter. The in-wall subwoofer in particular is going to cause headaches. Also, I think it would be better by far to do the main speakers in-wall, not in the ceiling, for the reasons you've already cited. But PM Robert Zohn and see what he advises.
one of the other Davids