1) 0 feedback
2) it's HIS responsibility to give you an accurate address
3) tell him he needs to send the item back if he wants a refund, cut your losses, and write his name and paypal on an excel sheet, and block the account.
4) fuck him.
shit happens all the time, he's just trying to get a discount figure.
if he wants a refund, he needs to send the item back and you need to verify it arrived in the same condition you sent it in.
if it's not, contest it with photo proof like you did in the thread with the previous pic, and ebay will likely side with you