There is a reason to meet your professors in person. You can only email your professors once a day to ask about grades but you can ask them in person as many times as you want. That way, you can limit your studying to the amount actually needed.
The professors don't have a special category on the Relationship panel but they do have a special relationship with you, which is shown on their individual panels. You'll just have to look at every sim you've met until you find the ones that say Professor. They are usually sims you haven't met before unless you've been hanging around the universities.
