It's been quite some time since I lived there, but Oxford is definitely a college town. There is little there that doesn't revolve around Miami. It's a cute town with tons of coffee shops, bars, and locally owned stores. It reminds me of a smaller Ann Arbor (although much more conservative). There is also a little bit of friction between the "townies" and the college students, although I suspect this is directed more at undergrads.
The undergraduates are mostly white and upper-middle class, although there is more diversity amongst graduate students and faculty. Fraternity and sorority culture is huge, as are sporting events. However, academics are also valued. There is a wide range of course offerings, which probably doesn't interest you as much as a grad student, but you can take credit classes in wine tasting, horseback riding, yoga etc. There is also an ice skating rink and a huge fitness center. Miami brings in a ton of guest speakers from all different backgrounds. I saw Colin Powell and Henry Rollins within a couple of months of each other. For such a small town, there really is a lot to do.
As far as part-time jobs, you'll need to be prepared to drive 45 minutes or so to Cincinnati, or at least the 25 minutes to Hamilton. As I mentioned, there really is very little in Oxford that doesn't revolve around the campus.
Hope this helps.