Cage moss doesn't stay moist for long and it can harbor bacteria so I personally wouldn't use it unless the snakes going into shed. I tried to use some for one of my beaked snakes but he had nothing to do with it. A thermostat will control the heat which you need because some uth's can get hot enough to cause burns to your snake. A thermometer will just measure the temp and a probe one is best because you can test multiple spots instead of ambient temp. You want to pay more attention to ground temps as bp's spend a lot if not most of their time on the ground though I've seen some balls that like to climb, so ambient is important as well.
If you have the dial gauges, then they're a waste. Wal-Mart should, or at least they used to sell an acurite thermometer that had a probe and measures temp/humidity and I'd go with that over an analog gauge though some analog humidity gauges can be calibrated for accuracy.