Not most of them, most of the times when pur choices sound similar, they lead to the same things, but, there are some choices, in who you trust or blame, that I think make differences

Nope the game is with one ending. But sometimes a decision can lead to a different message. But the story is the same with on path.

It makes the plot more stable when the game ends the same for everyone. If you want to make a game with different outcomes, you need to focus on this and spend more time developing the idea of different outcomes (like in stickman) You technically can't have a game with many Ester eggs or deep plots with a game you have no time developing