Ok nice, didnt know that, thanks.

So the wallet.dat contains puplic/private keys, transactions, and the block count where it got all previous transactions ?

If i didnt use a wallet for some time, it will rescan the blockchain i got on my disk without downloading it again? Is there any status shown on the client which tells me if the wallet is up to date with the blockchain dat files?
Because i didnt really notice something like that so i guessed its better not to recieve coins on wallets which arent currently 'loaded' while updating the blockchain with another wallet.