Some of your questions depend on when your son graduates. I do not believe coaches can contact him till the summer before his senior year.
As far as recruiting goes, how will he know if schools are interested? Will they contact him after camps?If they are interested, you will know, they will be in contact and set up school visits. My sons experience is that the schools that were most interested contacted him once a week.
Should he ask for honest evaluations of where he stands?Yes, you do ot want to waste your time and energy on a school that is not interested.
If they are interested and he "commits", how will he know for sure if he has a spot? Technically there is no commitment in D3. Some kids that commit never show up on campus. I believe most coaches will be honest and let you know were they see your son fitting in. I believe most of the schools in the conferences you mentioned will let a recruit knows where they stand. Ask a lot of questions and go see some games so you know the talent in the program. Then compare honestly to your sons ability.
ADL- Wow that is surprising. I expected a double header but not two. Should be fun. I look forward to getting up to CWRU's field.