Are these to make a hole in the rock or cut a round cab into the rock or both and what diameter would you go by for the round cab if I wanted a 14mm round cab?

I suppose you really could try to do both with these. None of these would work for making a 14mm round cab though. the largest size available here is 11mm. You would probably want to get something with about a 15 or 16mm OD in order to get a 14mm round cab. Keep in mind you may have a hard time removing the core from the bit without chipping or breaking the stone.