Hi Mr Speeed,
Thought i'd chime in since I'm trying to work on a Saturday morning but am not focusing on work very well
For the in cabinet specifics (dimensions, toe in, recomended cabinet heights etc...)I'd check with Axiom directly (Brent/JC/Alan).
As has already been said, the QS8's will be fine separated on the back wall, they are very forgiving on placement and tend to sound great in most situations.
There's no such thing as too much speaker for the room. You control 'too much' with the volume and subwoofer gains!
Go big and indulge whenever you want too.
Lastly on the built in sub placement - just be careful on committing to that. I know I had the same plan myself and built a spot for my EP500 at the bottom of my equipment rack. Unfortunately the bass was very 'lumpy' with the sub placed there and I had to move it. That space is now used for PS3 controller chargers, BRD storage etc... I would have planned differently if I'd known in advance. I also recall Micah (sort of ex forum member) had similar issue with built in placement of his sub - it looked great but was not good for sound. Try the sub crawl if you can before you commit to the placement of a built in horizontal sub - you might save yourself headaches in the future.
OK, back to drafting release notes (i.e. work) now! Thanks for the diversion.
Cheers,
