Here's the thing. Don't worry about satisfying some perfect checklist of prerequisites to becoming an FBI Special Agent. The Bureau is an ever changing entity and they hire people with backgrounds to meet their needs at that time. You'll hear people tell you accounting is the way to go. Then the next person will say no, military training is the best way to get in. Someone else will say study Arabic. Just realize that by the time you are eligible to enter the FBI at age 23, there needs may be very different than what their needs are today.
Here's the low down at the requirements to get in the FBI:
1. You must be a U.S. Citizen
2. You must be between the ages of 23 and 37 years old.
3. You need a 4 year college degree.
That's it! Everything else is negotiable and variable. Keep in mind that you'll have a REALLY difficult time making yourself competitive if you have a criminal history, financial problems, no work history, etc...
So, my advice to you is to pick a field that is interesting to you and is something that you would enjoy doing if you weren't in the FBI. A foreign language is nice to have, but learn one if you are really interested in learning it. Just because Farsi and Arabic are tops of the list today doesn't mean anything. tomorrow it could be Chinese, Russian, or something else. By picking something that you enjoy learning about, you will improve your chances of being successful at it. And remember, you have until you are 23 until you can apply to the FBI. You'll have to do something between the time you graduate at when you apply. Might as well be in a field that you enjoy. The FBI looks for people that are well rounded and well adjusted. If you try and force yourself into a mold you think they want, you might miss out.
You asked about specializing as a criminal profiler. Profilers in the FBI work at the National Center for the Analysis of Violent Crimes (NCAVC) at Quantico, VA. Its pretty competitive for Special Agent's to get assigned there. But if you do, you would basically be support to case agents in the field or doing general research. You would be doing things like review crime scene photos, interviews and reports, and other evidence of of a case in order to discovered who the subect (bad guy) is. It is very interesting work, but you'd miss out on the regular case agent type stuff like breaking down doors for searches and arrests.