I just moved my vampire crabs into a new tank with a bit more land. They really appreciate substrate they can burrow into and the water portion really only needs to be about 1/3rd of the tank. Put some wood on the land portion that they can burrow under. The crabs themselves will consume many things, be sure you have an organic substrate that they can eat. I find that mine consume dirt for the majority(75%) of their diet. I use coco fiber mixed with orchid bark, aragonite and sand. Put some aragonite in the water portion to help with more calcium diet. If you find that some of your crabs don't have the bright "glowing" eyes, don't fret. This apparently just means that they're juvenile.
Here's a great link for info and inspiration:
30 Gal Paludarium How-To and Journal
And here's the paludarium I had them in:
40gal paludarium journal
Good luck with your new crustacean friends!