Good luck. You'll need it.

How are those fellas doing, Sman?
I'm a pool filter sand user. It's nine bucks for fifty pounds here, coarser than most sand, and pretty. The larger grains make it sink faster and it doesn't get sucked up into the filter as easily. they can dig just the same. I've ranted about it many a time.
I would recommend a breeding group of multies, a male and a handful of females. Naturally, you'll want to start out with a few juvies and dump extra males later. No tankmates, and my trio is more than happy in my ten. Just bred this morning.
They don't NEED shells on top of shells, but I'm sure it would help. And don't do much more than an inch and a half to two of sand if you go with these guys. You'll want upwards of two shells a female.