Sure, the North Koreans hate the film, but why do these cinema companies give half a shit? They weren't going to get North Korean ticket sales regardless of the movies content.
Yes, absolutely.
I don't share the ideas, but they certainly aren't rare.
These are fringe beliefs. As a general rule, movie studios do not shitcan movies just because a couple of dumbasses think that the movie goes too far.
Seriously, if Harry Potter was released despite the controversy it caused, there is no way in hell that "controversy" around The Interview is the reason behind this decision. You'd have to be incredibly out of touch with American society to think otherwise.
I roundly reject the speech of shitty people. (I've switched tabletop game stores because I have no patience for GamerGate partisans, for example.) While I don't agree with the notion that this movie is deserving of rejection, I sympathize and anybody who feels that way is not somehow wrong by refusing to accept and patronize it.