I think once he is cut from the Browns, he will do his best to stay out of the headlines. Doesn't mean he will succeed, but he will at least try to stay out of the limelight. I think in Cleveland he realized he did not want to be there, and did some of what he did to get them to release him. As with any thing Johnny has done, not the most mature way to handle a situation.
As to why someone would want to take a chance on Johnny: Brian Hoyer, Nick Foles, Case Keenum, Matt Cassel, Brandon Weedon, Ryan Mallett, Matt Schaub, Mark Sanchez, Austin Davis. These are QB's who were either the starters for their teams, or started several games due to injuries to the starter. Johnny doesn't have to be Joe Montana to improve to the point where he is better than most of those guys.