Single-family house south slope - floor plan planning, tips?

... is nonsense. It is clearly recognizable here as a builders' forum and not an architects' club.

You asked whether "one" plans the ground floor first, or what we recommend: normally (GF = entrance and living floor, UF/AF = sleeping floor) I advise starting with the upper floor because it is more detailed. Besides, as a layperson, one "thinks" the downpipes more easily "from above."

Then you stated that regional architecture was actually born out of necessity. Yes, but that is basically the root of all regional building cultures. And you certainly do not distance yourself from it: I see your design as very D / A / CH alpine, and in basic outlines it would look the same if built 300 years ago from log beams. Except for bathrooms instead of washing at the well or in the mountain stream, it is practically an original alpine hut or a Maiensäß. Where a toilet is, you tend to make the room as narrow as a bowling alley. Narrow stairs, cozy cramped spaces, the alcove, the walk-through pantry, a herdsman would have built all that very similarly back then. If you tell tourists that the practice was once a sheep barn, they would believe it.

With all due respect that every family may have its very own culture of coziness, it seems to me this only explains a small part of the peculiarities of your planning style, and a larger part is due to awkwardnesses that one may naturally have as a layperson.

A professional, who also does not have to be "a city dweller" and can culturally understand you well, will in my expectation find a "more generous" architecture. Especially in mountains – as said, very similar to each other in D / A / CH and also I – much building culture is reinterpreted, i.e. respectfully transferred into the present.

Exactly! The "mountains" in "Erzgebirge" should not be understood as "mountains" in the strict sense, but at least there are still real winters here and quite popular ski resorts. An alpine architectural style is therefore not directly out of place.

But we do that, even regularly! But more has to come than a drawing like "Die SIM 4," which we have actually already had once

I am curious about the floor plan from the planner.

EDIT:

The 3 floor plans basement, ground floor, upper floor together have 250 sqm of living space. I leave out the attic. You skillfully did not count all the hallways.
Also, the basement has living space quality, meaning it costs as much as the ground floor and upper floor.

We calculate for new buildings in 2019 with 2000€ per sqm of living space or 400€ per cubic meter (at least my architect calculated that in 2018).
Which surprisingly fits well with a medium good standard for many. And that without additional construction costs (house connections, civil engineering, drainage, fees, architect, energy consultant, etc.), outdoor facilities, kitchen, garage, etc.

I think it's becoming understandable now! I am also currently building with an architect, with a basement and hillside, so I know what I'm talking about when I tell you that your 480k€-500k€ will not be enough. Unless it is a shell construction and you do everything, absolutely everything yourselves.