Auto focus is not required, and would be a hindrance. You should simply focus at infinity, that will be sufficient for any images without a large telescope and very high density. I believe HiRISE has to worry about the difference in focusing at 300 km vs stars/Earth/etc, but this usually isn't a concern.
Photos could end up washed out if you have the sun in your field of view, or near your field of view, this can best be prevented by putting a shield of some kind around your lens, such as a lens hood. They won't be perfect, but they will help you to improve your protection.
The biggest concern, however, is one you haven't mentioned. The platform stability is critical. Take a camera without flash and take a picture from a car, at night, etc, and you'll see that the platform must remain stationary, or else the pictures will turn out poorly. There are a few ways to manage this, the key ones being:
- Use a short exposure.
- Keep the platform stable, using gyroscopes or other similar.
- Using an adaptive technique, ground post processing.
The first two are preferred, but the third can be used in some cases.
If you want to do this, I suggest you first figure out your requirements. What kind of exposure will you need to get the picture you want? How much camera shake are you willing to have? What pixel density do you want? What is your weight and power constraints? All of these must be considered to find the system that can best work with yours.