I use a similar setup on a chest freezer and it's worked great for me. I went with the ebay aquarium controller which is a bit cheaper than the Ranco (I think I paid $25, plus another $10-ish for misc parts). Unless you already have a Ranco it's worth checking into as it might save you some coin.
As for the heating, I use a variety of fermenters (stainless conical, glass carboys, Better Bottles) so I went with the Brewers Edge Space Heater stuck to the wall of the freezer.
I'd recommend using a small fan to keep the air moving, and make sure your temp probe is in contact with your fermenter and preferably insulated. For mine I sandwiched the probe between the fermenter and a spare piece of rigid foam insulation.