I have had my account for too many years.... I'd have to go to their site to get answers to some of the questions

Yes you have to tie the account to a checking account and I think it really helps overall if you give them a CC account as backup....

As I recall - you the seller or person receiving the money pays a fee. You'd have to look on PP's web site to see a schedule of the fees.

It probably wouldn't be a bad idea to have a separate business checking account.

PP can tie up monies (amounts) that they've transferred. I believe that can only happen when there is a dispute.