The stairs really don’t work like that. You are building over at least 2 steps with the bathroom, you’ll hit your head there. 1 step is okay with normal ceiling height. That means at the bottom of the stairs next to the front door you are only allowed to “step out” 1 step. It also works with 0 steps, we have it like that going towards the basement. The stairs then become about 4 meters long. Yours is only about 3.30 or so? It fits on the upper floor, but the hallway becomes smaller, the lower children’s room gains space, and the bathroom has to get a small corner. The basement stairs do not work like that at all at the moment because you don’t get to the starting point. The living room wall is in the way. So you would have to turn these stairs twice, starting from the entrance hall. I would definitely make a turn with 0 steps so that no steps are “standing around” in the hallway. All in all, it will work.
I don’t see a storage room of that size on the upper floor, you have a huge basement and a central vacuum doesn’t need 7 sqm. I would either plan in a small office there (at least a large roof window so it can later become a cozy office) or put the utility room with the washing machine there. People don’t really like to work in the basement with light wells nowadays.