...answering your question...!

Just having a quick go on the keys, I suggest something like this, based on my UK keyboard : -

Left joypad = keys around the "S" key. (AWDX, possibly QECZ as well)
rear left button = Blue modifier key or Ctrl key
rear right button = Enter or backspace
C-up-left-right-down = right arrow keys
B = B
A = N

The external keys are no good (camera etc) as it is not comfortable to hold.

Big problem is analog. I thought about the accelerometer but if you move during a game, then it would activate the joystick.. Perhaps use a modifier key, so key+accelerometer = analog joystick?