Yep, the gameplay gets boring pretty quickly. I didn't even realise that the numbers were people waiting; I thought that's were the people in the elevator wanted to go to. I also agree with your other points. Though I would like to add that it is sometimes impossible to reach certain floors. Since the zero button doesn't work, the lowest the elevator goes is to the offset + 1 (offset = +2 at the start).
Yeah I noticed thet too, but that's because the ground floor is listed as floor 1, that's why you can't use number 0.
I think that some floors are unreachable to force you to make some choices over the passengers, I think the idea behind that is to give way to the passengers that you can actually take to the right floor and leave the others on board waiting. I don't know maybe it's just my take on the game ahah