I think TO is better suited as an interim AD. He could help calm the waters and be an effective consultant in finding a replacement AD and if needed, head coach. A new hire with his stamp of approval would bring fresh blood, but keep ties to Husker tradition.
DR was a great player, but I have no idea what his qualifications are besides being an ex-Husker player.
I have no objections to Pelini or Gill, but think it best for everyone involved to let the past be and move on. Having either one onboard may prevent some people - fans, employees, players or whomever - from letting it go.
As with the new AD, a new coach who is hired in a different manner than Callahan and has the stamp of TO's approval could probably complete the healing process of the last few years and bring us back to glory.
Just my uneducated opinion.