Putting an STF-2 behind the TV would work fine. You definitely need a sub of some kind. Just measure the space to ensure there's room, inc'l cable clearance. Your system will give a good experience.

I personally favored a 5.1 config with QS8s, reasoning there's currently relatively little 6 or 7 channel material. However there will be more 6/7 channel movie soundtracks as time passes.

Since you're 50/50 HT/music, I'd suggest getting a couple of DVD-A discs to try out surround music. The DD 5.1 soundtrack will work in most any DVD player. If you like it you could then get an SACD or universal player.