-I have the public adress, Is it possible to verify that it is on blockchain.info so i don't waste my time to try to find his ID?
When you say public address are you talking about the Bitcoin address? If so, you can't get a ID/Email or even any info from the address itself.
-He only have one e-mail address. Was it possible before to register on blockchain.info without giving your e-mail? Blockchain's Id recovery doesn't send him his Id ...
I can't remember but if he doesn't have his ID and he can't recover with any email, then there is no way to find out his ID. Sorry =/
The only thing you guys can do is try to find his ID in any PC/Email he had in the time he owned that wallet.