Hey, I understand it's my fault. My second question is still unanswered. I'd appreciate it if you can answer it.
If I understand your question, you want to prove to mtgox that you own the address that the funds came in from? If you still have the wallet (and private keys) that is possible.
They can have you sign a message using that private key, that would prove that you own it. I have no idea if mtgox actually goes through this procedure though, you will have to ask them.