Some temp gauges are better than no temp gauges, but those analog dial-type ones can be pretty far off. If you're looking for the Accu-rite everyone talks about from Walmart, it should be in the hardware section with the outdoor thermometers.
As for the dimmer, here is the one I had before I got my thermostat.
http://www.homedepot.com/h_d1/N-5yc1...atalogId=10053
The heat pad plugs in where it plugs into the wall, almost like a plug-extension. Then there is a cord with a slider to increase or decrease the current to the plug.
As for what can happen, if the snake doesn't move himself off of the heat (which can happen if they choose security of the hide over thermoregulation) your snake could end up with a nasty burn. I don't think that moving the heat pad to a different enclosure will really make a difference. I'd just recommend getting some kind of heat regulation going ASAP...