A few questions about vampire crabs

[starsnsand]

I've yet to get some but here are my questions:

Is cocofiber okay to use instead of a sand substrate?
Is moss required?
Can I use bottled water?
Is a heat mat needed as I know they can live at room temperature but I'm not sure if there would be enough humidity without one?
Do they need to eat fish or would locusts/crickets be enough as non-veg?

Thank you in advance if anyone responds