Your texting plan includes text, picture, and video messaging.
Also, I used WiFi quite a bit my first month with this phone and ended up using less than 150 MB. As long as you're careful about how you use your phone when you're not using WiFi, you should be safe. Even though you'll be living on campus, that doesn't mean that you'll be spending all of your time on campus. Just be aware that emails do count against your data plan (even when you use it while WiFi is available) so don't send or download huge attachments from your phone if at all possible. Also, I would download an application manager like Advanced Task Killer Free. The last thing you want is a browser that's still open in the background refreshing and reloading pictures when you're not on WiFi. If you notice that it's not enough (and you need to do more), try turning off background data (which will turn off the transferring of information that some of your apps may do. That should really help control data flow.