I'm going to venture a guess that breeding hermits would be like breeding most other fish.... you want to do it in a separante tank, as the lil ones will become food for everything else that you have in the thank with them. Some species i have seen writeups on will eat their own young, so you need to even remove the adults.
Most crustaceans have a planktonic stage if I remember correctly from my school days, so you might have to look into alternate forms of filtration and water movement in your breeding tank, most little floating organisms hate impellers.
I would be interested in reading any web pages that are out there on breeding crabs, seems you could make a killing on emeralds with the prices they are going for in the LFS in comparison to their size if you were able to sell directly to them.
GL