Having lived in Columbia all my life, and gone to Mizzou for undergrad, I am a "little" bit familiar with the area. The only subject I am not much help with is apartments, as I opted to live at home instead of taking out a loan.
The locals think the mall is terrible, and several stores are threatening to go out of business, but it's decent and St. Louis is just an hour and a half away. Dillard's, Penny's, Target, Barnes and Noble, Sears, small food court, and smaller stores as well. Near the mall is a Macy's, Toys R Us, Best Buy, Hobby Lobby, Michaels, Old Navy, Gap opening soon, etc. There's a Kohls in town, Bass Pro, Joann's Fabrics, and several more.
As mentioned in previous posts, it is very much a university town. Off of the top of my head I can think of six other campuses around town in addition to Mizzou, so most everywhere has some sort of student discount.
Speaking of which, two movie theaters in town that range from $5-12 depending on time of day, 3D, student ID (must be with you), etc. Also, something called the RagTag Theater that shows documentary-like and lesser-known movies. That one's downtown in what looks like a hole in the wall sort of place.
Shakespeare's Pizza was voted number one college hangout in the US about a year ago, it has three locations and is always a favorite. Lots of chain restaurants (Applebee's, Ruby Tuesdays, Lone Star, Red Lobster, you get the idea). A new favorite that just opened up a few months ago is Cheddar's, a less-common chain that serves amazing home-style food.
Cars are very handy, although as mentioned above, it is a very bike-friendly town and campus (says everybody but the locals that drive, but as long as you follow the rules they'll like you!). There are three Walmarts, three HyVees, three Gerb's (smaller grocers), a Patricia's (local grocer), and some local markets that are scattered around town. As far as traffic, I live outside of city limits on the southeast side of town and in order to get to campus at 8, I leave home at 7:30 and that gives me time to drive to campus, park, walk the 5-10mins to my class, and be there five minutes early. Non-rush hour is even better, I usually leave around 20 til. I'm in an organization on campus and have parking there, not in the commuter lot, so that all depends on where your class is and where your parking spot (if you're driving) is.
Nice big public library on the corner of downtown and far edge of campus that I think is pretty good.
The airport information is up to date from the previous post. It's all American Airlines and Frontier right now, but Frontier is pulling out in May.
Hope this gives you a jumpstart! Anything else you'd like to know?
M-I-Z!