Sand is easier, but I have them all in normal sized gravel they are fine with it.
They get only a little larger than an inch
golden in color
They filter feed and reqire almost no miantenance, but you can use invert food if you like.
I am not sure where they come from origanally. Mine came from Texas. I bought off a guy on Aquabid.com. If you want detailed info, go there and look at one of his auctions. He has a very good write up on them! I do know that they don't have a parasitic larval stage like many others. This is cool!

I hope I helped!