Davey, I'll try a few of your questions. I've never heard an MTM center that works as well as a vertical center as similar as possible to the mains. In Axiom terms, I'd suggest an M2 to go along with M22s. The unique configuration of the VP150 apparently avoids the MTM problem and should be the choice over the VP100 if a horizontal center is used. In your room the M22s with a good sub should be plenty of kill, although I wouldn't term the M60s "overkill".
On a receiver in the price range that you're considering I'd suggest the Pioneer 53TX with its automatic MCACC speaker calibration and equalization over either of those you mentioned.
In your size room, unless the speaker wire paths are unusually indirect , standard 16ga lampcord is all you need.
