You do not need to do all this.
When you have backup of wallet.dat - you can just put it into bitcoin-qt corresponding folder (after you will manage to get it to work again).
Or else, you can create online wallet and import your wallet.dat backup there https://blockchain.info/wallet/import-wallet

But, if all you want is just know balance -
1) create new wallet using pywallet
2) import all addresses and private kyes
3) open this wallet using bitcoin-qt
4) goto help-debug window-console (this is on Windows, but I suppose on Linux it is the same)
5) write command getreceivedbyaddress XXXXXXXXXXXXXXXX(insert address here)
If address is not in your wallet - you will not be able to see balance on it