Re. the center choices, it's a bit a matter of how much off axis performance you need. I don't see that being a big concern in your room layout so I wouldn't worry. Also Some will argue that the horizontal driver layout of sideways center channels, like the VP__s, produces an effect called combing that is considered undesirable. Others will say it's audibly negligible, others (like Axiom's Ian Colquin) might even argue it's benefits. Personally, I can't advise you on this. I will say that I very much like my VP150 and envy the 160s and 180s.
Others will have much more educational answers.
By unused wires do you mean wires that come out of the wall but there is no speaker there yet? If so, what I would do is terminate the wires on a wall plate like this one. Stereo Wall Plate
Then when the time comes, you can plug in speaker wires of the required lengths terminated in banana plugs.