I just posted a picture thread over in the invert section: Geosesarma crabs
I have a group of Mandarin and a group of Red Devils. They are very easy to care for and breed well once old enough and established.
I keep both of my groups (2.2) in Fluval Ebi tanks. I use the fluval stratum substrate, and I layer several small pieces of ghostwood on the bottom to set up little nooks and crannies for the crabs to hide. The substrate stays wet - and I have cleared substrate away towards the front and set up a little pool area. Then in the rest of the tank, I have ghostwood branches covered in moss and miniature orchids (Pleurothallids primarily). While the branches are more the benefit of increased space for planting - the crabs will climb all over them (and sometimes knock the orchids over if not yet well rooted).
They are most active in the evenings, but also in the morning. For feeding, I offer a mix of HBH hermit crab food and hermit crab pellets (crushed) to which I add additional calcium carbonate and also some astaxanthin to help with color (and I find it makes a big difference).
As for breeding, they do it all on their own. One day you will see little tiny crabs running around. I let them grow in the tank until they become about 4-6mm carapace length - and then pull them. With my two female Red Devils, I pull about 40 baby crabs or out every 6 months or so. My mandarin crabs seem to be slower breeders, but I haven't had them as long.
Here is a poor pic of one of my tanks.