I scan at 150 dpi when I draw in pencil, it doesn't really matter since I ink on the computer.
Uhmn, a good size for a beginner to start at is 4x5, its also rather cheap compared to the other sizes. That's still the size I use, though I think I might upgrade soon.
Anyway, what I'm working on now :
Писатель всегда будет в оппозиции к политике, пока сама политика будет в оппозиции к культуре.