Regarding Paypal...I thought if you did do a charge back to paypal, they would close (suspend) your paypal account, or something like that.
Alot of people don't like the way paypal and ebay operate, just google "paypal account locked".
I've sold on ebay also, and I had to give a valid CC number, as well as a valid email account which you had to respond to email they would send you (I think, it's been years since I set up my account).