The racial, religious, LGBT, and other groups on campus put on wonderful events that most often, all can attend. The groups are meant to foster community between people with commonalities, but also to bring awareness to those outside of the determined label. The shows, events, programs that these groups put on at USC are always a lot of fun. I am not a member of any such group, but whenever I go to events I feel welcomed and leave informed.
I think that USC is so big and that there are so many different people that hardly anyone would feel out of place. Sometimes it is harder for some to find their place than others, but basically everyone I know feels as if they are part of both the larger community of the campus as well as part of a less broad circle, yet never confined to either.
Most students wear jeans and a t-shirt to class. A lot of students wear USC gear. Sometimes female students will accessorize or wear casual dresses, but it is usually very relaxed and what you would expect in Southern California. A lot of students wear sweatpants and comfy clothes to early morning or Monday classes.
It is hard to describe four different tables at USC. Because there is such an interaction with different types of people, you can't really generalize. At a couple tables there are students finishing up last minute homework or leisurely reading. At another table, there are so many people crowded around, likely a floor ended up coincidentally congregating for dinner, that they have trouble fitting their food on the table or hearing each other over the five simultaneous conversations. At other tables there are groups of three or four people casually discussing their day, and once in a while you will find these people engaged in a topic of fierce, yet civil, debate.
Students at USC as a whole are not as politically active as they are at some other schools, but they are likely more active than one would expect. The school gets a reputation for having an apathetic student body. I find that it is more half and half. Half of the people I meet are politically aware. About a quarter are politically active. The thing is, a quarter at USC, while it may be a quarter, is a whole lot of people. You can find many politically active people if you know where to look. There are many organizations and events centered around politics that I just make sure to go to. The students I talk to are predominantly on the left, but that is because I am and I go to the events more closely related to this political sphere. Although, I know some centrist people and a few people on the right. I think it is a mixed bag, the proportions are largely equal. I would say that the most active branch would be the left one.