Can anyone show me a rule, case play, or simplified and illustrated diagram that says an out of bounds player must place 2 feet on the inbounds playing surface to establish inbounds status?

I was taught that only one foot needs to touch inbounds if the other is airborn.

Take a look at:

http://www.officialforum.com/thread/20717

4-35-1
The location of a player or nonplayer is determined by where the player is touching the floor as far as being:

a. Inbounds or out of bounds.
b. In the frontcourt or backcourt.
c. Outside (behind/beyond) or inside the three-point field-goal line.

Note that there's no requirement for two feet.