I would find out about admission requirements.
Find out about what high school courses they want incoming freshman/students to have taken?
Cost of tution, room and board?
Opportunties for schlorships, grants and work study?
Do they require freshman, sophmores to live on campus?
If they plan on having a car at college, are they able to park close to the dorms, class etc? Cost of parking?
If your son knows what he wants to major in, see if you can see the degree plan (courses he will need to take in college)
Is there a wait to get into that major? Some majors are so popular, the colleges have limited seating, they may have to wait in order to get into that major.
Question about school safety.
Question about dorm safety.
What is enrollment?
Describe college life there?
How big is the town the school is located in?
How far is food shopping, restaurants, etc?
Is shopping accessible by car, school shuttle bus, etc?

I would see if you could get an official tour that would include going in buildings, classroom, lecture halls, student center and various types of dorms.

Once you decide or narrow down the collges, I would visit during the school year to observe college life and if the college would be a good fit for your son.

Good Luck!