You'll probably find as many good and bad fans in Columbia as anywhere else in SEC. Not the worst in the conference, not the best (in terms of mean/nice). Like most SEC schools, avoid tailgating near the students (unless wild drunken debauchery is your thing).
Best non-reserved parking is back half of fairgrounds, but you'd better be there early to get a park there. After that it's a smorgasborg of smaller lots. If you know someone with a reserved park up close who is putting on a tailgate you can park and walk. Reserved parking areas around the stadium are nice and are where the best tailgating occurs. If you're okay spending a few bucks try to score a reserved parking space online from someone selling, worth it if you can afford it.
If you're seats are on the East or in the endzone, bring a hat & sunscreen. USC does permit you to bring in one unopened bottle of water, so take full advantage of that & save $4 for your first half bottle. I think they've added some water fill stations to, so in theory you can make it thru a game without buying water.
I'll come back and add as game draws closer. If anyone is looking for hotels look out at Harbison area, lots of nicer hotels there and the interstate is a straight shot to downtown - avoid price gouging of downtown hotels. Don't be afraid to go AirBNB either.