>>195951781. Hogan was coming off a bad divorce and needed money. Himself and Bischoff were a couple of sharks who found a themselves a money mark.
2. I dunno what to tell you but the momentum TNA built by 2006 hadn't grown much in the three years after, despite putting on a better show than Raw or Smackdown at the time. TV ratings for Impact were similar to WWE's failed ECW C-brand and PPV buys consistently underperformed. From TNA's perspective they thought a proven draw like Hogan would be the answer to start growing again like what happened with WCW.