I wouldn't recommend a task killer. Does more damage than good to Android. Linux/Android comes with decent memory management and will free up memory as and when it's needed.
A great remote for your phone to control your PC. Install this app and download the server program on to your PC, and you can control just about every aspect of your PC via your phone. I use it a lot when watching movies on my PC for volume control, pause, changing movies with the file manager etc. There's a free version, which has just about everything I need, but the paid version comes with more remotes.