Usually upper division courses are easier to register for, since upperclassmen tend to be specialized., so the classes invariably have a space or two available. As far as recruiting, that could be an issue. People I know were able to get internships during the summers, and had that experience on their resumes to contact the college recruiters directly. Please realize that companies do come through a university, but these same companies have college openings they are trying to fill, whether from on-campus recruiting or otherwise. I do not think there is an advantage to meeting a recruiter on-campus. In the end, it is all decided centrally, at the company headquarters.
If you are proactive your senior year, and use your career placement services to help structure the process, you certainly can interview with whomever you choose, without requiring them to come onto your campus. I highly doubt there are a certain number of slots reserved for graduates from a particular college (yes, alumni preference from hiring managers may be a factor, but experience will trump that).