It sounds like a mild sensory issue even if it is one at all. I think if it made you feel better you can get evaluated by an OT and she can do a sensory checklist with you. If the chicken nugget thing annoys you, try not serving them for a while then try again in a few months and see if you get the same response. The tags in clothing thing, some adults have that issue-they sell so many shirts without them now, just look for them. I wouldn't worry about him-my son has global delays too but is not on the spectrum.
My ADHD son is now in the Air Force taking things apart and putting them back together. He always enjoyed doing this such as, taking apart watches, toys, door knobs, and anything else that he could find a tool for. This is actually a gift and I hope your son uses it in the future. It is amazing how well ADHD children can focus when it is something they enjoy. I believe a lot of ADHD people have this ability.
Was your other son evaluated by an autism specialist? If not and you are still concerned, I would schedule an appointment with one.