I see. In bitcoinqt they don't really tell how much money I have in each address. They just tell total. ALso if I send money, they don't tell me from which address the money is from. Just what's in it total.
Go to
http://blockchain.info/ and type yoour public address into the search bar, that will tell you how many coins you have.
The best way to transfer coins at the moment is to send them over the network, so send from one wallet to another. That is the safest way. Also having the same wallet or address on several computers has been warned against. I stick to best practices myself, 1 unique wallet per computer and send coins to the wallet that I want the coins to be in. I have never tried to import export keys. If you do just check that they actually have your coins!
Good luck!