I too have a few questions about thermostats because I'm completely new to the whole deal and I've never actually seen one in a set up before:

Do you keep the device inside the cage or out?
Do you put the probe on the hottest spot?
Do you set the temp on the actual thermostat?
If you set the temp on the thermostat, what's the point of having a thermometer except maybe for the cool side?

Sorry if these are really stupid, I just don't want to do anything wrong. I'm sure if I had one in my hands I could figure it out, but I'd rather know before I go and spend tons of money on one =] This is the only part of setting up the cage that's confusing me