I will do it if I can afford to lose the item, and if the buyer has plenty of good feedback. I'm talking about stuff that cost me a few bucks that we might be selling for $13. Definitely not on anything expensive!!!
Yes, you can change the label. After you click "purchase postage", look on the left side of your screen where the buyers addy is, then click "edit address."
Ebay will, in my experience, send their form email to the buyer saying that the item shipped, but a few months ago, they were not updating the edited address. I always snap a pic of the label in case the buyer throws a big ol' fit, like the last one did.
Ebay also told me that I would be covered if the buyer had emailed the address change...but that is what Francis said, who works in an ebay call center in Bangladesh.