Downsizing

 In the process of downsizing my audio gear. Just don't have the room for the big speakers and rack system anymore.
I've never sold anything on Audiogon before so unsure of the process and the in's and out's. Done some searching, but nothing found to answer all my questions. Maybe you can help? I've sold items on eBay before, but nothing this large. And I figure this would be a better place to sell.
1. I see listings state, "Paypal add anywhere from 2% to 6%". Why is there such a wide range? Is it a higher percentage cost for higher priced item? Does Paypal charge to transfer money?
2. I have some large, heavy items, McIntosh MC-402 & a pair of B&W N802's. The Post Office won't pick these up. Suggestions on companies to use? I do have the original boxes.
3. Returns. I see a lot of postings that don't take returns. Is this a normal practice? Spending this amount of money, to me anyway, I think returns are only fair.
4. I see people rating their equipment, "*/10". Is there a guide for this or is it subjective? Difference between 7/10 or 8/10?
5. Anything else I'm missing?

 Thanks, appreciate your comments.