While his son or daughter might have a better chance, you still can try.
Birth Certificate: Go to the State of Maine (I mean contact them) first. If you know the city and county, that would be where I'd start. There has to be a birth record somewhere.
SSN: Take the Birth Certificate to the Social Security Administration... the local office. They'll be able to help you... or direct you to whomever can.
Once you get his SSN: contact military archives:
http://www.archives.gov/veterans/evetrecs/index.html Schools are going to be tougher. It's highly unlikely that the military's going to have any such records. You really have no leads there.
You might also check with the local Veterans of Foreign Wars post. I don't know if they can help, but they seem to be able to gather information on a lot of stuff. But if I were you, I'd make this a lower priority. Let them know what you want and why, and see what they say. But this is really a shot in the dark.
It's probably going to be time-consuming. So be patient.
