Buying the Onkyo HT S7100 7.1 package

[iam1bearcat]

After BizDaddy mentioned this option to someone in another thread, I looked it up and decided this would be perfect for me. I only have to connect my blu-ray player and PS3 (for now) so the 4 HDMI input is just right for me, but since this is my first HT I have some set up questions for when I get it.

1. I know I should get new speaker wire, but what size? 14 or 16? And what is really the difference?

2. I'm guessing this system can be upgraded so if I want new speakers eventually, I can do that with this system, correct?

3. I know to give the sub alot of space because people said it heats up, should I also give the receiver alot of space too? I see alot of pics on here where people just pile stuff on top of their receiver, does this cause any issues or is it fine?

4. Does the sub connect to the receiver via HDMI or a different cable?

5. How far away should I put the front main speaker from the TV and other items? Do they get any interference from each other or are they good wherever?

Thanks for the answers, excited to be ordering this beast soon.
(And for the space and price I'm considering, this is ideal for me so please don't say "well get this instead it's only 2 grand!" haha, because I'm not looking in that range).

Thanks.