gump

Hello everybody hows it going? We are in the process of building a new house and I am needing some advice on setting up my home theater system. I have read tons of articles online but I like first-hand experiences better.

I currently have a 5.1 but plan on upgrading to a 7.1 in the new house. Right now my speakers aren't set up the best because of the shape of my room however the new place I will have a 18' x 18' room (I already heard square rooms aren't as good as "slimmer" rooms) to set up in.

My questions:

Speaker placement and height
Receivers I need a new one. (Really don't need anything to fancy)

... and for future use what about the best bang for your buck projector and screen? I looked at a couple at some local shops but couldn't tell the difference between a $5k and a $2k.

Thanks in advance