Please do not bring any bad or negative attitudes with you! Rome is not for whiners and complainers. Leave all that behind you.
No need to bring any snacks or food items from home. Maybe a jar of peanut butter if you think you will crave it over the semester. Many open markets in Rome sell fresh fruit and vegetables, as do stores such as Castroni and a drugstore at the train station (Termini), which also carry American products.