Yeah, it's best you get in-wall rated wire. I don't think it's actually code, but the best way to go. Use a decent gauge. Just go with 12 ga.
Speakers a the most personal part. You need to decide what you like. Just don't buy Bose.
On the DVD player, a good upscaling player will do much better than the receiver. That feature in the receiver is really just for simplicity of hookup of various components which may or may not have HD/digital outputs. You don't need to get a bluray player. The
Oppo DV-980H does a stallar job for less on regular DVDs and has the ability to become region free with a simple remote command. So, it can play DVDs from anywhere in the world, which is a big feature for some people, like me.
Don't buy Bose.
I would try to put a rug on the floor to tame the brightness.
An alternate way to get multi-room audio is with an Apple (works on PCs too) AirPort Express working with iTunes. That way you are wireless.
Don't buy Bose.