That's an amazing setup. Thanks for passing it along. I was planning to put wiring in for a projector at some point in the future. But seeing this, hmmmm, I wonder if I could cobble together enough denaro to get the screen and projector in now. My wife definitely wants the 52" LCD out of the family room and into the basement, but I saw a setup at a local AV store with a retractable screen covering a LCD display - the LCD for the morning news or short programs and the big screen for movies and sports.
The pulldown over a flat panel is extremely expensive, typically, for the screen because now the screen needs to be tab tensioned. This means a 4 digit increase in price. If you go for it, and mount the LCD high enough to do 3 identical speakers, check out Seymour's tab tensioned.
Otherwise he sells the material as is for DIY. You are doing all this theater DIY, so that means YOU have the ability to save a TON of money, if willing to build the subs, build the speakers, build the screen, etc. There are a bunch of us here who built our Seymour screens, GO-NAD! being the most recent. I'm taking about $300-400 bucks for the whole screen, including the blackest of black velvets meant for telescopes, to the straightest wood you can possibly find, and guess what, George Lucas uses the same exact material in his home.
Run wiring for everything, 9.1, even 11.2, whatever, speaker wire is so darn cheap from Monoprice in bulk, and that's even as 12 AWG. Do it now when it's easiest, and think conduit conduit conduit when the walls are down. I don't know about the quiet rock and its cost, but the typical method for isolation is staggered studs, insulation, double dry wall, with green glue in between. If you start a thread at AVS dedicated theater subforum, people like Ted White or Dennis Erskine may give you better pointers on where to place critical beams or doorways, in terms of best reduction of sound transmission.