Hi Paul, I would advise you look at what the best images use in the categories you mention.
I am not an expert but a few points.
Modern CMOS cameras can quickly download large numbers of pixels with USB 3
Nyquist does not really apply to area detectors like CCD and CMOS cameras and greater oversampling is needed.
If I remember correctly planetary imagers go for about 0.1as.
Regards Andrew