1. Apology, I hope you do get to see a copy of this message. See my reply to Ol' Uncle Bob.
2. Did you contact the National Archives and records administration (NARA) at College park, MD? These guys have the official histories of the battalions in Panama.
3. You do not state exactly when your relative joined the 767th AAA, or left it. But I have deducted he was transferred into and left it sometime. My reply to Uncle Bob states the 'continentals were to be transfered out" except a few to train drafted Puerto Ricans. My guess is he joined a different unit.
4. It does not matter what his job was regarding unit. Every unit up to battery level has a headquarters unit, and if he was in this headquarters unit he could be repairing communication lines. If he was at regimental headquarters, he could be in a service detail or detachment serving the other components of the regiment.
5. See a reply to Wiswar I will cover unit organization in a general way.