with speaker systems, re: the adequate power needed, watts/channel or amps? thanks

How about price/features? I'd say that's the most important thing. None of those others is going to matter if you're looking at a decent (ie, not a $100 Kenwood surround) receiver.

Here is a link I have used to get ideas about some receivers and how they perform. Maybe this will help you.

http://www.geocities.com/Area51/Hollow/3401/ratevsac.htm