The STC-1000 is a great solution. For the probe question, the best way is to use a thermowell. But if your like me you don't have a good way to use a thermowell with your carboy. In that case, I tape the probe to the side and then I tape pieces of a koozie over the probe. That at least gives some insulation from the ambient temp.
If you can find an old upright freezer on Craigslist or something (got mine for 50 bucks), they make great fermentation chambers when coupled with an STC-1000 controller. During the summer, my controller cycles the freezer to keep things cool. Now that temps are dropping, I have a small space heater inside that plugs into the outlet controlled for heating by the STC-1000.
This cheap heater does a fine job. (though it was only 10 bucks last year...)
http://www.walmart.com/ip/Lasko-Products-My-Heat-Personal-Heater/16503222