I alwayst try to pound intp people you cannot do enough pre-planning.
The rock is up but:
Do you have RCA out for a sub? Make sure of it, or in several location and use the one that is suitable. If there is a conduit for the overhead video, I'd pull in another set of video source, just in case, perhaps component or even s-video? Power for the projector? Normal ceiling height of 8ft usually doesn't need a lift. Over 9ft ceilings do. That needs reinforcement up there. You may want to make notes which way the ceiling joists are running and how far apart, 16" standard, or more at times.
Keep up that good relationship with that knowledgeable person.