Tuffy,

The water should be the same temp as your tropical fish aquarium water. That is normally in the high 70's to low 80's. It feels slightly cold to me, but people are different, so just keep it the same temp as your fish water.

He will not eat until after his shed.
A humid hide will work fine for him.
Substrate is your preference. I use newspaper or Bed-a-Beast. If you use cypress mulch, aspen, or something similar, make sure you don't feed him in that cage. You don't want him swallowing the substrate.

Welcome to the site!