OMG that is one big butt.
I agree with Doughboy B, I always cook butts a day ahead so there is no surprises getting it done on time, then warm it to serve. Tastes
just as good as if it was just cooked and takes away all of the stress.
The sand comes bagged at any home supply or building supply (Lowes, Home Depot). It's clean and ready to use.
I have only changed mine once because I keep it covered to keep it clean.
You only get dry food if you over-cook it. I think the majority don't use water but I could be wrong.