You are correct,
For planetary imaging the more aperture the better. Most of the time a webcam is used to capture thousands of frames in a very short period of time.
For DSO imaging you will need a EQ mount that is accurately aligned with the Earth's axis allowing you take long expsoures. A DSLR or CDD camera is used.
With your setup, you should be able to take great widefield images.
I'm sure more experienced members will help you out.
