Depends on your definition of catchable. The umpire is to judge an IF if the batted ball COULD be caught with normal effort by an infielder, pitcher or catcher. And that judgment is supposed to be made at the apex of the ball's flight. If a ball goes up over the IF and the umpire believes that is could be caught with normal effort and no one moves to make the catch, by the time is descends, is it still a catchable ball? Regardless, it is still an IF
The infield fly rule is to protect the offense, not the defense. If there is a pop fly at the edge of the grass and no fielder moves to catch it, it is not an infield fly. My problem with the application of the infield fly rule is with umpires who don't understand the purpose of the rule.
An infield fly MUST be a catchable ball.
It should be, but it may not be. The fair batted ball must simply be able to be caught, in the umpire's judgment, with normal effort by an infielder, pitcher or catcher. I'm confused by your statement. To me, "catchable ball" and "be able to be caught" are the same thing.
An infield fly MUST be a pop fly, not a line drive.
"Pop fly" can be a subjective issue. There is no "height" requirement, just that it not be a line drive. I am again confused. If it's not a pop fly and not a line drive, what is it?
An infield fly MUST land in the infield. If the ball lands in the outfield, it is not an infield fly.
This is absolutely incorrect. See above I can see that it would be possible for a fly ball to land on the edge of the grass in the outfield and still be called an infield fly.
In your opinion, is the situation described an infield fly?