Given that Bologna is a student city, your options for food are virtually endless. Generally I'd say that in Emilia Romagna you eat well, but slightly expensive compared to the rest of Italy. No seafood (for obvious reasons).
Also, as soon as you're in the vicinity of the two towers, the entire city centre is within walking distance. If pilgrimages are your thing, you can also choose to walk to San Luca. It's famous more for the portici than anything else though. And you'll get enough portici in Bologna anyway.
Nightlife depends. Used to be that you could just hang out in piazze with beer and wine (and you'd have some pretty interesting conversations), but they've made that impossible now. Because I was a student when I was there, I just kind of went with the crowd. We'd something completely different every night. Not sure what you're into and with what sort of crowd you'll be hanging out though?