eBay

i am a noob at this and im wondering how this all works. Do you weigh the item before you post it and then print a shipping label for the exact weight you calculated? And what happens if you have an item that's like 10 pounds but you print the label ...

So i have an item that was bidded on, and the winner of the auction refused to pay me the winning bid and told me he would only pay an earlier bid of his. Me being new to ebay and was kind of out of it, accepted and he payed me through paypal... now ...

I've put in the wrong payment email on an item im auctioning but it won't let me change it in "edit". Do i have to cancel the auction and do a new one or will i be able to edit this?