In November my 6 yr old and I were in 7 airports, and cleared security in 5 of them. The process was an absolute non-event from my point of view: walk up to the conveyor belt, we put down our bags, shoes and jackets in the bins, through the metal detector, claim gear, and on we went. Of course, I made sure both of us were wearing no metal at all, so as not to set off the obvious metal detector.

I also explained to my son in advance what to expect, including shoes in the bin, as he ended up wearing light-up shoes which I have read, right in this very forum, can cause issues going through security.

As for the international aspect of your trip, I'm not sure the actual TSA folks will even notice if you're making any domestic flights - the only 2 ID checks we experienced the trip were by the line organizers, who I believe are not TSA employees.