You might want to check this out for GPIO control - http://davidhunt.ie/?p=2641 and I have just started my RasPi Camera Controlling and until I get a camera that works I can't take the next step. The next step for me is creating a web page to control the camera so then I can use any web browser on the network to control it. Last but not least I bought this battery pack and got 7 hours of RasPi on it with video playing 85% of the time - http://www.amazon.com/gp/product/B006VYXH6S/ref=oh_details_o02_s00_i00
Have a great day.
Rich Shumaker