Ahhh, Salamanca. Sdp, studying there is wonderful. Unfortunately I don't know anything about those two schools, but I could help you with the housing. If you stay with a family, they can only give you certain rules. For example, they can say you aren't allowed to call out from their phone or bring guests home. But they can't give you a curfew or tell you you can't receive phone calls. I lived with an absolutely incredible family in Salamanca for 6 months and had tons of freedom. The issue is more about courtesy, such as let them know if you won't be there for cena and remember to turn off lights when you leave the room. There is a residencia estudiantil in Salamanca but I don't think you can just say you want to live there, it is for some special purpose. Apartments are easy enough, especially if you are going at the beginning of a semester as people whose roommates who are done studying will need new ones. Apartments are very cheap there as well. But, being biased, i have to say try to live with a family! It is the best way to learn culture, food, slang words, how Spaniards relate to each other -- all sorts of things it would be difficult to learn staying with other foreigners.
Ask away on any other questions -- I could talk about Salamanca for years!