I am not sure that I know the answer but I met the problem
I fond that after you are running extrimly simple camera application, it helps to fire your main application right away. Try it, I am not sure that it will help, but it will be interesting to know...
I'm not clear what you have said. Can you explain it a little please?
Some times when you are trying to access the cam from your main up(that usually have lots of data inside) it make the cam to crash the app, there is an unexplainable solution that I found to fix this bug, just make a small app that just present the cam on the screen, you will have better chances to make it work and then the main app in some unexplainable way also start working.
I am also not clear about this, but it just happened to me a lot, aspashely when trying to put my app on new device.