IMHO they are not really "dwarves"although some may not agree. I am looking at a 4+ inch female as I type. I keep em on 5+ inches of peat,big water dish,and I moisten one side of the enclosure.Throw in a slab of corkbark and your set.They WILL dig/burrow,so be sure to allow them to do so.They are also great webbers.
In general, slings of a lot of species tend to burrow more than adults. I have two C. fasciatum, both of them quite young still, and I hardly ever see them. But the times I DO see them, oh man... They are beautiful little buggers! Especially right after a molt!
They grow as fast as you feed them, just try not to over feed them.
The girls will get to just over 4", but not much bigger. The males won't get that big.
Keep the humidity up on the slings, until you start seeing color, then they seem to like it a little drier after that.