Welcome!
1) Yep, that is what I did to save money, same speakers so why not. A 60 is a 60, a 350 is a 350, etc... no matter where you buy it from, they are still brand new.
2) The 60's will perform better in the mid-range and high's category in my opinion, and most likely have better bass response. That is a pretty big room...
3) If you buy from local retail stores you will pay MSRP, unless you wait for good deals. I waited until one of my local stores had an employee cost day, and got my Denon 2805 for 20+ % off. There are lots of reputible etailers online also where you can save money, just make sure they are authorized. There are lots of good receivers out there in the 400-600 range as well from the above listed brands.
4) Can't help you on this one, I prefer a front projector/screen combination over a TV anyday.
