Sounds like a rather nice place in EP - both volatiles, carbon compounds and likely heavier stuff, so one can build more or less anything needed. It seems that the asteroid belt is wetter than we previously thought. Hmm, mining these volatiles might still br tricky due to the low gravity (0.015 G). I would guess one good approach is to cover a part of the surface with a fine web, crush the regolith and ice underneath, close the sack around it and move it to a processing unit. People with too much hightech might want to have a nanotech web that does the processing in situ like an indoors recycler, but I think it is safer and easier to make use of a big "rocksorter unit" that does preliminary separation of components and then leaves the fine purification to specialized disassembler units. Also, when characters have a firefight on the surface stray shots will likely produce small steam explosions that can push away unwary characters or creating obscuring debris clouds.