There will be about 500 students entering in January after NU In. Your country group will have at least 50 students that you have been with for four months. They will be the core of your friend group from which you will branch out.
If you look back on the threads in the Northeastern forum from December there were a couple of NU In alumni who posted about their experiences abroad and back in Boston.
Here is one thread:
http://talk.collegeconfidential.com/northeastern-university/1972330-nu-in-admission-details-northeastern-university-in-p2.html