There is no way to correlate a priv key to an address. You will need to compute the pubkey, and then pubkeyhash, and then the address. You could use a tool like bitaddress.org to do this.
Quite the contrary; every private key correlates to an address, how else would you be able to access the bitcoins they hold? However, it's most certainly not something you'll easily be able to do by hand.
An offline copy of bitaddress.org (as suggested above, and in my opinion the best option) or a bitcoin client would fast and secure (and can be deleted/shredded afterwards if necessary), while using something like blockchain.info requires you to trust control of your private keys to someone else, which is never a good idea unless necessary.
