Deborah, think you may be barking up a tree that will give you very little info and what you do find out will be of little value.
First off, he was not classified. He held a security clearance. Just about everyone held a clearance of some type even if they did not know it. It is called trustworthness. Just having a copy of a unit roster was considered to be confidential. If the roster contained more information such as MOS and rank, it might be classified higher. In todays military, you cannot go about the E-5 level without at least a secret clearance.
What this means is that he may have worked in a signal corps unit or Army Security Agency or one of its early incarnations. It does not mean that he actually needed a clearance, just that he was 'around' classified information. In my particular unit, even the cooks had a top secret clearance. The reason was that we might be discussing things that maybe we shouldn't and they may hear it so they must be indoctrinated not to pass that information along.
Shoot! A newer form or RADAR gets developed and it is immediately classified. You may no nothing of RADAR but you work at an an airport. You now need a clearance.
Assignment and travel restrictions were in place because the military did not want you placed in an area where you might be interigated. If you know something about crypto equipment should you be taking a tour in Moscow? No, that was a restricted area as far as you were concerned.
Your item 11 reads (National Agency Check) NAC completed 13 August 1953 by USAFFE, Secret (background investigation) BI completed 12 November 1957 U.S. Army Europe Top Secret.
My question to you would be Where did you live in Europe as a child? Do you remember any place names like Bad Aibling, Rothwestern, Augsburg, Pocking or Memmingen?
While I was over there, we had an individual who decided to vist a border that we were not suppose to be within 10 kilometers of. Like an idiot, he stepped across the border so a friend could take his picture by the sign. 10 weeks later, the country in question returned him as he really did not know anything. He earned a DD and a free trip home to the states. Young soldiers, sailors and airmen will do some of the dumbest things sometimes. Thats why there are travel restrictions.
No, the U.S. military felt that many things were of interest and classified them. We today wonder why. A chow hall's rations was sometimes considered classified because it showed how many troops were at the barracks or when a large amount of troops would pass through... We are left to wonder 60 years later why "600 ham sandwiches" ended up being classified secret...