1) Yes, any move GM likes, but a move must be made. "OK, door is now open, nothing else of note happens" isn't on the table
2) Yes, any move GM likes
3) No, if a move is triggered, it's rules take effect (that's what "if you do it, you do it" means)
This is one of the reasons I dislike Dungeon World specifically: moves in that game are just poorly thought out which leads to weird situations like above. If it was like "When you use your extraordinaire strength to destroy an inanimate obstacle" it probably would be better, so, like, it can't be triggered by normal things anyway, and only a Fighter can display strength superhuman enough to, idk, break through a massive door secured by a huge bar.
3) in particular, that damn "if you do it, you do it" is a great strength of PbtA, but also a common failure point for some hacks, including Dungeon World.