If predators cannot get underneath it, that should be fine for them
If digging appears, I would run a few strands of electric wire around the bottom to help deter predators.
Otherwise it should be fine.
A tarp isn't needed as long as they have a place to get away from the elements.
For bedding, try to keep 6 or so inches. Dry shavings/hay/straw mixture is what I use but it doesn't matter as long as you can keep it dry and warm for them
If digging appears, I would run a few strands of electric wire around the bottom to help deter predators.
Otherwise it should be fine.
A tarp isn't needed as long as they have a place to get away from the elements.
For bedding, try to keep 6 or so inches. Dry shavings/hay/straw mixture is what I use but it doesn't matter as long as you can keep it dry and warm for them