I suspect your problem will be much more fundamental than pan/tilt. Your platform is spinning on the end of a pendulum. It is possible (but non-trivial) to account for those and point your instrument.
One of our teams just took a crap-load of pictures and used some software to stitch them into a nice hi-res panorama.
As for pictures of stars, not sure how much luck you will have. I’ve never seen any stars in our balloon pictures, but with a controlled exposure of a pointed SLR it may be possible.
Oh yeah, make sure you aren’t pointing at the sun; you can easily fry your sensor, especially without the benefit of the atmosphere filtering it.
There is very little atmosphere, so heating via directly-attached heating elements is generally more effective than other methods.
Condensation is also a big issue.
I’d get a cheaper camera (e.g. one of the older canon cameras that can run CHDK), and a video camera, and do some testing before I flew the D50.