Some things I noticed:
1- When you empty your app wallet and for example 500mQRK is available, you can only send 499mQRK. It seems that there should be minimal 1 mQRK left on your app which is not visible anymore.
2- It would be nice if there is a button that you can select that QRK only synchronize when it is connected to WiFi.
3- The exchange rate is not working for my App.
4- You can turn off the background synchronization now, but it is not easy to do. Can there be just a "turn off" button, which close the QRK app completely without background running?
The feature I don't understand is "request QRK". Can that be explained? To my opinion it is a strange request

1- The app does add a 0.00010 QRK transaction fee to each amount of coins that is sent. Therefore, if you empty your wallet, the recipient will get the entire amount less the transaction fee. With the desktop client, it is possible to send some coins for free, if certain rules are met. However, it is not possible for the app to know all the information to see if a transaction can be free. The transaction fees go to the miners.
2- I will look into a Wifi only sync feature.
3- Not sure why the exchange rates are not working. The app uses Cryptsy then BTER to get the information.
4. The best way to turn off background sync is to press the back button (from some testing that I have done. It may not work in all cases).