INT on an IF
 

IF situation. R1 fron 2B collides with F6 (camped out under the fly ball). INT called at the time of collision. If F6 somehow recovers and makes the catch, we still have both outs, correct?

NCAA ball, not that it's relevant.

Doesn't matter if F6 recovered and caught the ball or not. Infield fly, batter is out and you have a runner interfering with F6, immediate dead ball and runner is out for interference.

An infield fly, under the infield fly rule, is just the same as any other fly ball except the batter runner is automatically out to remove any force outs.

Correct, but there are easier rules to apply:

Both NCAA (12.17.2.2 Effect Exception) and USA (8 7 J F) have explicit exceptions for interference by a runner on a fielder fielding a fly ball (of which the infield fly is an subset). Interference by a runner on a fielder effect: runner out, BR on first. But the exception(s) include the BR being also out (and USA takes if further, the ball does not need to be over fair territory; NCAA the ball has to be "fair"). Regardless of the infield situation, you get two outs either way.

I don't know why umpire want to get so much in a tizzy about the IFF and interference where these exceptions exist.

Now, NFHS is a different animal. NFHS does not have the exception to the runner interference. There is where you have to apply both rule effects (interference and IFF). I really wish NFHS would add the exception to make it the same as USA.