Smokey -
I've read most of the sources you mentioned, and will soon look at the others. I just recently heard Dr. Joe Chandler (Atlanta Braves team orthopedist) talk about this subject, which he has been studying for years. He reported a significant correlation to high pitch counts (both pitches per game and pitches per season) at young age to the incidence of serious arm injuries.
Given all the evidence that's available it seems that the pitch count police might be on to something.