Hi Dave,
I agree with your question #4 and 5. I think you are trying to ask too many questions at once. I'd suggest trying to decide what you want first, then what you want to spend, then start looking. Used guns that you can buy in the $1000-2000 range can be of a quality that will never be made again, and darn sure not found in what you can buy new, for that money. You won't learn much by reading gun reviews other than that the reviewers are usually full of crap, barely re-writing factory release letters. You might learn some specs, if you know what specs you are looking for.