There are actually 4 Iowa coaches in the Hall. I forgot Eddie Anderson. He spent most of his years shitting indoors.
Ferentz has had 7 teams finish in the AP top 25: 02, 03, 04, 08, 09, 15 and 18; not 6.
That is correct, Iowa was #25 in the final AP poll (left out of the coaches poll):
http://www.espn.com/college-football/rankings
https://collegefootball.ap.org/poll