i tried posting on the nghost fourms but was getting some really bad latency, so i'll make the posts here.
1. xstroke to control nghost with gestures. i've set up xstroke to work with mplayer on my car pc before, with it already having binds for pause, fullscreen, and volume control it worked pretty much out of the box. make sure that if its code is integrated into nghost that it still draws its line of what it thinks it saw, it helps with troubleshooting touch screen problems alot, because if its jumping around you know why it won't recognize your strokes.
2. voice recognition. i'd sugguest using pocketsphinx from www.pocketsphinx.org. its cmu's voice recognition engine, i've been using it for the past year, and could build the required files for recognition pretty easily for a fixed set on input words. its also got information on how to integrate its code into other apps. if you decide to go with it feel free to pm me and i can help you get it functional.