Hello. Studying in Puerto Rico is a great idea.
PR is a nice place to spend time. Do you speak any spanish?? UPR is a great school but most classes are in spanish. If you want english courses I suggest InterAmerican University also in Rio Piedras. Here we dont say Flats do that will sound wierd to people. You can rent a casa(house) or an apartamento/condo or maybe you can stay in a dorm with students. Rio Piedras isnt the best part of San Juan but it has good parts near the University. Food is about the same price as in the US. San Juan has transportation, outside San Juan does not really have any. Please look below for rentals. GOODLUCK!
http://www.clasificadosonline.com/Rentals.asp