I am going to warn you..do not get hermits and mix them with snails!!!
I had a large hermit and he ate a baby trigger, shrimp, 20 snails, emerald crab..all in a week.
Also, my tiny tiny blue and brown legged crabs (1/4 inch) gang up on my snails and take their shells too!!!
So all I can say is..I am CRABLESS forever. I don't even bother with them.
If I were you I would suggest different kinds of snails, brittle starfish (in awhile when your tank is a bit old)
I once I didn't drip water from my tank into the baggie from the LFS
and a few snails must have died from shock. Make sure to be patient when acclimating so that the temp AND salinity can even out.