Of the three schools only Ponce and Caribe take out of state residents. I would apply to both but Ponce is definitely the better of the two. I was accepted to both and picked Ponce in a second. You'll see a huge difference if you visit the schools. Both are LCME accredited but Caribe has ahad more problems in the past with its accreditation. Ponce was just reviewed last year and got a 7 year unrestricted accreditation.
You don't have to be 100% fluent in Spanish to be accepted, if you have good conversational Spanish that is enough. Everything official is in English; tests, quizzes, handouts, labs, discussions etc. The only Spanish you need in the first 2 years is to understand the professors, most speak Spanish although there are a large # of American professors in the Biochem and Physiology departments.
All in all I have been very happy with Ponce. It is a friendly, laid back school but also prepares you very well for the boards and for residency. Last years class had quite a few students that rocked step 1 with cores over 150.
If you have any questions let me know and I will try to answer them.
Good luck,
Adam