Adamant:
In terms of the interview...Just relax and be yourself. As always, be prepared to answer the usual questions: Why Medicine?, Tell me about yourself?, Extracurriculars, Etc. Be ready to say why should they take you instead of the many other applicants. Also make sure that you know your spanish (I say so because in all the interviews if you are form the US they may interview ou in English but will check that you know your Spanish). You will have two interviews, one alone and one will be other current applicants.
Ponce is cheap! You will be able to find a nice place to live for 500 and food is extremely cheap (ie. a combo in McDonalds is 3-4bucks , here is like 7 dollars). If you like to cook it would be even better. So you don't have to worry about that. The area is very safe and the school is close to Plaza del Caribe (a big shopping mall with pretty much everything that you may need). On plus there are many other attractions and in PR everything is close (1-2 hours driving will take you to any place that you may want to go).
About UCC, I do not really know much, but I don't like Bayamon to much. That area is more "caliente" and I think is is even more expensive than Ponce.
Let me know if you have any more questions. Keep me posted on how the interviews go. Good luck!
RetroMan