I have had a buyer change the address on eBay before. I am not sure if they have to do it through PayPal or eBay but it can be done. I think if they are "verified" on one address, changing to any address also works fine.
Refund doesnt give you FVF but if you cancel the transaction you get a FVF credit.
How did she get 80% feedback as a buyer?
She got a neg as a seller and 4 positives as a buyer.