That would work just fine. I think I would figure out what each of the lettered settings get you in terms of temp and record it somewhere. Temp control isn't a big deal, as long as it gets as cold as you like your beer, with a keezer/Kegerator as it is with a fermenting chamber.
Take a gravity reading. It is the only true way to get a handle on how well yeast are performing. It is possible that it fermented if you had krausen, but it is also possible that it did nothing. Without taking the initial and final gravities you have no baseline with which to work.
No problem, you might be able to find them cheaper somewhere else online, but Mc Master is one of those places that has just about everything so sometimes it seems easier to pay a little more for the convenience factor and there a reputable company.
What are you using for a mashtun? There are weldless kits for thermometers for cooler as well as keggles/kettles. Most homebrew stores online have them like this:
http://brewhardware.com/measurement-devices/thermometers-71/88-dial-thermometers
If you go with this company, you an contact...
You looking for something like these?
http://www.mcmaster.com/#cam-and-groove-gaskets/=s0rs9d
and this stuff for tubing?
http://www.mcmaster.com/#standard-plastic-and-rubber-food-grade-tubing/=s0rtm3
Hope that helps