I'm pretty sure that pywallet found your altcoin wallets.
Again, except maybe for some crazy ones. Try pywallet to dump a wallet from an altcoin, if it works, it's 99% sure the recovery would work
The keypool is a set of 100 (by default, but you can change it) "hidden" addresses. They are used for change (and generation if you are a miner).
By the way, you can add a pool address yourself. Using the pywallet WUI you can add a dummy address (private key = '000...001' for example) to a wallet and tell it to make it a pool address.
Yes, this would dump your recovered wallet. I misread, you asked if you
should. Well it's as you wish... If you put that in the file, then keep in mind that there will be unencrypted private keys written on your hard drive.
If you have the recovered wallet, rename it 'wallet.dat' and put it in the bitcoin directory (~/.bitcoin) without forgetting to backup the current wallet.dat. Then
bitcoin-qt -rescan