I must laugh at this one!
Even though, with all due respect, you are an architect(presumably by trade) as you are stating, asking for some input from people on an audio forum website will not get you the information you need to give your client anything remotely approaching WORLD CLASS HOME THEATER!...sorry to be the one to break it to you dude. (AND CERTAINLY NO OFFENSE OR IMPLICATION OF THE KNOWLEDGE, EXPERIENCE, OR QUALITY PERTAINING TO ANYONE POSTING HERE OR SIMILAR!)
I say that not as being snooty, arrogant, or confrontational, not at all! I say that as someone who's been an exotic custom home theater designer, die-hard audiophile, consumate audio/video tweek and hobbiest, high end AV salesman, acoustical engineer, and just plain been around this stuff since AV began!!!
Basically, you can't put it all together in any kind of timely manner to possibly get your man the goods here..if you do sincerely value his money, time, experience, and results that is!
What it respectfully sounds like you're asking, is akin to asking a few people who've seen a transmission out of a car for information on how to build one yourself! I think you're expectations might be a bit lofty! And that's not insulting anyone here. And maybe my analogy is a bit off, but I think you get the picture.
My advice is to consult proffesionals who actually know what it takes to design/engineer/build/install/calibrate/oversee a competent project such as your suggesting, and contract the work out!...or at the very least strongly consider consulting extensively! Just makes plain sense to me.
You simply will not be able to accertain and obsorb all that is necessary here. It takes years, dedication, knowlede, experience, and commitment to excellence to get what you're asking.
May I strongly suggest your clients interests here over a monetary opportunity to "make the most of it going at it alone!"...not the best situation I think. I'm sure you're client would agree.