I don't know the answer to your freezing question Laura. People comment that they and those around them see positive changes in both physical and mental aspects of themselves, but I don't know of any empirical data about freezing.

Re the road bike vs spin cycle, I like the road bike on a trainer better because I can adjust the seat and handlebars more precisely, i.e., in smaller increments than on a spin cycle. Both bikes have easily adjustable resistance. Either kind should work for you. You really want something that is stable and that you can get on and off of safely. It's also important to have cages or clip on pedals to hold your feet straight, especially on a road bike where a jerking foot could get caught in a spoke.

Today in Puyallup several people got on my bike to give it a try. Even though I'm only 5'2", some people had difficulty getting their leg over the bar. In those cases I recommended a recumbent stationary bike or an upright with a "girl's" crossbar. Safety first.

Glad to hear you're getting a bike. Please keep a journal. I'll be eager to hear your reports. It takes a while.