We also have tilt-and-turn windows. I think they are great for floor-to-ceiling windows that you go out through. I wouldn’t do it again for normal windows because you always have to open the one fixed window first, and the second window doesn’t have a normal handle but an inward-lying kind of latch. It’s not a big deal, but I wouldn’t pay extra for it.
We also have a side entrance door in the utility room. And I wouldn’t want to miss that. When we are at home, it is used more than the main front door because it leads directly to the back garden area, garages, and sheds.
Regarding the sanitary fixtures: you have to decide what you like and whether you can get something better for the price. I think you can.
The same applies to the stairs, it’s a question of what you prefer. I have a bungalow but also know houses with stairs. And I would always prefer an open wooden staircase if I didn’t necessarily need a closed space underneath, because it simply looks lighter and more open. A friend of mine has a concrete staircase with closed sides, which to me looks like a prison.
Tongue-and-groove boards can be easily installed yourself; you have to see what you can get yourself. Last year we paid 10 euros per square meter, but directly from the sawmill, found via classifieds.
You have to talk to the respective craftsmen about all the small jobs. Ours refused to do anything that wasn’t done through the general contractor because he forbade it and they wanted more jobs from him.
Whether you need a laundry chute, I can’t say because we have a bungalow. But I think you just go downstairs anyway and can take the laundry with you.
We also don’t have a ventilation system. I don’t know it and don’t miss it. Does it save a lot of energy? It also uses energy itself, even at times when not heating. You would have to look into that. At any rate, we achieve a good indoor climate with normal airing. I might be somewhat critical if really both partners are out of the house for 12 hours a day (but then again, the question is what you need a house with a garden for;)).