On mounting the projector ... After discussing this with Trevor, it was decided to screw the projector mount to the floor joists and have it stick through the ceiling.

[Linked Image from i.postimg.cc]

One worry I had was that the ceiling is designed to vibrate. If that transferred to the projector would you see it on the screen? This is probably a non-issue as I could find no mention of it as a problem but ... doing this made me feel better. It's also the way Trevor does it in his installs. 2nd it allows the option of mounting a heavier projector and 3rd a nice way to route cables (the pipe runs to some conduit which goes to the equipment cabinet).