@hopefully16 - Not all co-ops are paid, but the vast majority are. The exceptions are generally in things like music industry/arts where the companies can get away with it due to demand, small non-profits (for social sciences majors) that can’t really afford to (there are some co-ops that you have to be work-study eligible for to get paid), and some international co-ops (if you want to do a clinical co-op in Africa, for example). However, these are the definitely the exception. Also, there is a $6,000 Presidential Global Scholarship available if you want to do an international co-op.
On your question about 4/5 years/co-ops/summer classes: there is generally a lot of flexibility, but it can depend on your major. I was in behavioral neuroscience, and I basically had free reign over how I wanted to set things up. I started planning to do 3.5 years and 1 co-op (I came in with a lot of IB credit), but ended up sticking around for 5 years and 3 co-ops, which is the “traditional” Northeastern plan. I ended up not needing summer courses to fulfill my requirements, but I took one summer term anyway to meet pre-reqs for graduate school; it’s very flexible. Northeastern now says anyone can do 4 years with 2 co-ops, but that would require summer classes (unless you come in with a ton of credit). I wouldn’t get too hung up on avoiding summer classes; it’s very much part of the norm here, and as a result campus isn’t totally dead over the summer. (Also, Boston in the summer is gorgeous.) I believe you can find some example schedules online (perhaps through your department’s advising site?), which could be useful.
@holden14ns - kiddie covered your other questions, but on the party front: Northeastern is not your stereotypical movie-esque frat/big 10 school. There are definitely parties and I had plenty of friends who went to these bigger house parties. Since Boston is such a college town (300,000 college students in the Boston area), there’s also a ton going on that’s not Northeastern-specific. A lot of it, though, ends up being smaller parties off campus hosted by upperclassmen with people you get to know through clubs/sports/etc. There may be some parties where it’s harder for guys to get in, but that would be those bigger ones, whereas a lot of the partying I think happens on this smaller scale.