I have a SS Works kit on my sprinter... Uses R32 4pot Calipers from memory (I bought it 2nd hand so dont have all the info about em).
They fit under most 15" rims, however there are a few that are tight... I'm using SSR MK3s atm and needed a 10mm slip on spacer to clear the brakes.
And as to the question of 16" rims, I used to have 16" Buddyclub P1s and didn't do any suspension/body mods to make em fit, car was pretty low, too...