So I made backup's of all my wallets this weekend.   

But some wallets I couldn't find a "wallet.dat" file, for example the bytecoin wallet was, "bytecoinwallet.wallet"....so I'm assuming that's the same as the "wallet.dat" file correct?

Also, maybe a really dumb question, but I'm assuming the moment at which you backup your wallet.dat file isn't stuck in time at that moment with that exact amount of coins correct? 

Say I backup my wallet today and then put in another 10 coins into the wallet and don't back up the wallet.dat file again and my computer crashes, when I reinstall the new wallet on my computer and overwrite the wallet.dat file with the backed up one, does it show the new 10 coins or just the previous balance at the moment I backed up the file?

Hope that made sense!