re: Did out of bounds Bama player have to reestablish himself to become a legal participant

You only have to reestablish if you have been forced out of bounds and are the first person to touch the ball. That rule doesn't apply because it was already possessed before the fumble.

You can actually stand out of bounds on kickoffs, touch the ball if its close and get the ball at the 40. Same concept with the call on the fumble.

It was the right call. The bigger questions is what constitutes possession.