C.T.
Good day G., well I don't have much advise with the potty training...BUT the body part issue I know very well. My son now 6, found what he refers to as his willie winkie(I don't know where they come up with these names!)a couple of years ago and seemed to be obssed with it! It was uncomfortable for me but I just tried not to make a big deal out of it. I gave hom the speach about what and where it was appropriate and eventually he got used to his new found friend Willie and the foundling decreased(thank goodness).It is completely normal and a faze.
You have nothing to worry about he is just a boy, of course he is going to find it again in his teens,I would relax now and rest up for then.