I'll do my best to help you out with all your questions.
First things first, you should run wiring for 7.1 just in case you want to do that in the future (you mid as well, or you may regret it later).
I would use this wall plate to terminate behind your TV to goto your surrounds (assuming you run for 4 surrounds):
Cheap at monoprice. For your wire I would recommend bluejeanscable.com belden greyjacket in-wall 12g wire. Make sure you order about 20% more than you think you'll need after measuring all your runs...its always better to have some left over, than too short.
Bluejeanscable.com for your sub cable, I would use this for your in-wall installation:
Cheap at monoprice and you can terminate the with wall plates behind your TV and where you want your sub to go with normal RCA wall plates.
as for the QS8s, I just had the bare wire sticking out of the wall, and I mounted the QS8's over the hole in the wall, you don't see anything but the speaker, I used bare wire to connect to the QS8s binding posts.
You're going to need to know where you will be putting your couch and such so you can place your surrounds effectively.
here is how I layed out my room:
I actually have not ordered my 7.1 speakers, I only have 5.1 right now, but I am thankful I ran enough for 7.1.
