Craig,
Keep in mind that part of this is normal behavior for a child your son's age. My son Andrew just turned 5. Every time (and I do mean
every time) he has to come inside or leave a friend's house the waterworks start.
I understand that not all of this can be explained away, but rest assured, kids in general can be infuriating and a pain in the ass. In fact, perhaps we need a whole seperate thread for that.
Best of luck.