Does blockchain.info keeps my private key(s) in their wallets of database? I am referring to the wallets on their website.
What other private information do they use?
Technically,they don't.The wallet generation/authentication process is done on the client-side and no data is persisted on the server.That is why there are absolutely no ways of recovering your wallets if you lose access to your passwords.
Well they've got all of the private information you inputted when you signed up, or which they got when you signed up which is going to be email, ip, etc. And yes they do have your private keys, nothing you can do to get around them holding them.
Fuck off that's an outright lie.Please don't bother posting your option when you have zero clue about things.Makes you come off as a shit-posting idiot.