I have the same questions.
I have one final trip into the US (that was booked a year and a half ago) but it includes my teenaged children. I have started talking to them about NoS, what the images may be, what the options are should they be selected, what the enhanced pat-down experience is like (been through it 3 out of 4 of my last flights into the US), and trying to get them educated and involved in the decision. It is a vacation that they have very much been looking forward to, so if/when the time comes we need to know what we are prepared to do - and I think they are old enough to be involved in making that decision.
I haven't seen anywhere that minors are excluded from enhanced searches, but I keep hoping ...