I'm purchasing an A/V reciever capable of DD 7.1. I have a few questions on speaker selection. I know I need a sub, and a center speaker. I would like to use floor standing speakers for my fronts. Question? 1. What kind of speakers do you need with 7.1? 2. Whats the difference between satelites and surrounds? 3. How high off the floor should they be, I'd like to mount them on the ceiling? Thanks for the info.