I've studied Computer Science Engineering.
I don't know how many students there are at Carlos III but, since they are split into 3 campuses (Getafe, Leganés and the new Colmenarejo), you'll find it a very tiny university. I think Universidad Autónoma
has more or less the size of AUS. All the students at universities in Madrid sum up about 250,000 students. We have 6 public universities and a few private ones.
I think it's going to be difficult to arrange something on-line but you can try to e-mail the university. As I told you, Carlos III is fairly good "computerized" compared with many other universities. They should help you or at least give you some advice regarding flats in Getafe.
As for the Euro / Dollar exchange rate is something quite easy for you because 1 dollar is approximately 1 euro (currently 1 dollar = 0.89 euros). Therefore, just knowing the price is euros will give you an approximate idea of the price in dollars.