I got an on campus interview from a job and internship fair. Quick 15 minute interview with 3 alumni from my university. All of the questions were behavioral, but not really STAR. Very basic questions

Everything was handled very professionally. I received a call requesting an interview on Tuesday and was able to schedule the interview for the following Monday. All expenses were reimbursable. They paid for the hotel and then reimbursed mileage, tolls, food, and gas. On the day of the interview be prepared to wait a good amount of time between getting there and the tour as well as between the tour and the actual interview. Also note that you don't need to wear boots for the tour. Standard dress shoes with a defined heel will do. The interview itself was fairly straightforward. I interviewed with two different people, separately, from the same department. They really just went over my resume and then branched questions based on where the conversation was. As long as you are comfortable with explaining your past experience you will be fine.

The process is pretty long. I got called for interview for 2 positions. I went there early morning and went on a tour which was really awesome. After some wait, 2 people interviewed me for one o the positions. Then I took the bus and went to the other location across the river and had lunch with an employee. After that I met with the head of the department and then had another interview with 3 more people. I was there since 8 am and got done with everything around 2:30 or 3 pm.