Most crustaceans go through a planktonic stage at the beginning, and I don't think hermits are different. Other anomurans, like porcelain crabs, certainly do. I can look it up when I get home. Anyway, what this means is that the likelihood of any larvae surviving is about nil, because they will be chewed up by your pumps and eaten by your other livestock.
A lot of people (myself included) have lysmata shrimp, like peppermints and cleaners, breeding in the tank all the time. It adds a little high-quality zooplankton to the tank.
If you want to rear them, you might try to do it like the shrimp breeders do. One resource is a cute little book called "
How to Raise and Train Your Peppermint Shrimp ." It's a little amateurish, but an easy read and outlines the basics.
There are also posts about rearing crustaceans on the
Breeders Registry, but the site seems to have had a stroke. It opens, but very poorly. If it starts working better, try a search on lysmata.
Ruppert and Barnes' Invertebrate Zoology is an excellent reference for general crustacean biology, has a bit to say about hermits, and covers crustacean reproduction quite well. It's expensive, but most libraries will have a copy.
Edit:
Just did a little hunting around, and found a
site that says that hermits indeed have a planktonic stage.