Hello,
I don't know much about FIU, so I can't provide you with first-hand knowledge of the housing, food, students, etc. I did want to clarify one thing in the hopes of helping you find answers to your question.
In American English, "hostel" generally connotes an inexpensive (and often crowded) place for travelers to stay for a short period of time, for example, while backpacking through Europe (where I think such places are more common). The buildings owned by the university where students can live may be called "dormitories" ("dorms"), "residence halls" (may be like dorms, suites, or apartments), "student apartments", "student housing" (<-a common general term), or some number of other things - but generally not "hostels".
Now I'll describe some of the common housing options for students that are owned or operated by universities. Dorms often have 1-3 people per room, with a shared bathroom for all the rooms on the floor. Suites are like dorms, but they are arranged so that a smaller number of people share a common living area and bathroom, and they may have a small kitchen inside. Apartments vary in size and what they offer, but they more commonly have a full kitchen. There are probably some other types of living arrangements, but these three are probably the most common at U.S. unviersities.
Some universities have sufficient housing for all of their students, and may even have specific buildings reserved for graduate students. Other universities may have only a small amount of housing reserved for graduate students, leaving most students on their own to locate a place to live. Even if this is the case, and you have to find a non-university-run apartment, the university may have a housing office that can provide you with guidance about local apartment buildings, a list of vacancies and/or of people looking for roommates, a guide to how much rent you should expect to pay, a sample lease agreement, and so on.
At FIU, the housing office website is:
http://www.fiu.edu/~housing/
Hope this helps.
Namazu