I can speak from experience, as I was recruited by some D1 schools, and didn't have any support through the process--so looking back, here's my advice:
Sound advice to have a coach, or some other trusted adult w/ related experience there--such as a guidance counselor, any college placement staff at your son's school, teacher, or even a teamate that maybe has gone onto college recently.
Whether you have someone w/ experience there or not, there is no harm in being up front and telling the coach that you're not familiar w/ college life, etc. or running--if the coach starts going over your head with any explanations. A good coach should be able to speak to you, your son, and other family members/friends on your level and make you feel very comfortable. This is even more so when you/son visit schools.
Coaches are also very aware of financial concerns being a major issue/selling point, and will ask all the questions about your financial needs and let you know what they might have available for your son. This may not happen at a home visit, and subsequently happen in a later phone call, during a trip to the school, etc.
As far as determining if the coach/school/program is right for your son, a good judge of character will go a long way.
Depending on what your son's interests are in school, I'd ask about related programs to get an idea of what the school has to offer (and what the coach knows about the school, and how quickly the coach can get you in contact with other athletes or students, or teachers that are involved in a related major).
While you might not know much about running, the coach should ask your son (if he hasn't already) about his training in high school, and how the training in college will complement that, what might be different, etc. Good coaches should talk alot about opportunities through the school, instead of making promises (if you come to my school, you'll be conference champion in two years, making the 2012 olympic team, etc.)
Best of luck to you and your son!