I don't know, a lot of the home made mounts I have seen have used steppers, but having never used one myself I'm not sure what to expect?
I'm not to worried about triggering the camera, will be easy to do with a couple of optocouplers.
I'd like to use a arduino to allow me to fix tracking errors in sofware so I don't have to build a double arm or curved rod type, I'm just looking into the hardware side of things at the moment and would like to know where I can gears / belts / pulleys and things like that to fit the basic stepper?