If your gpa is slightly below the minimum in either category, you may want to discuss your situation with the faculty director, Steve Palmer. He may ask you to wait until the beginning of your final semester to see if your grades improve, or may suggest you begin your work by enrolling in CogSci 199. If your grades improve you may then be allowed to enroll in H195 during your final semester. Some major programs have thesis courses for their students. CogSci does not.
Students work independently under the sponsorship of a single faculty sponsor.
Occasionally, students have worked with two faculty members, though one is usually the primary advisor. Ideally, you will have become excited by a particular area of research after taking courses from a number of CogSci professors. You should be able to formulate a topic of interest through your course work and discussions with that individual. In some cases, students have an idea they'd like to explore, but don't know who to approach. Usually this issue resolves itself by the time students are seniors, but there are a number of other ways to narrow your search.