Single-family house with gable roof - improvement suggestions?

Of course, quite a bit of earth would have to be moved as well

That's still fun in the sandbox, but costs a lot of money when building a house. Digging an extra meter easily costs as much as a nice room; even the dog wouldn't pull the sausage off the plate that quickly.

3. The general contractor knows the result of the survey. Whether this was taken into account in his planning, I cannot say. We will talk about it.

Get yourself an architect who creates a house concept for you.
You can then implement that with the general contractor.

A sloped plot always belongs in the hands of a specialist who is familiar with it. Someone who only alters standard house types no longer has any feeling for the three-dimensionality of the slope.

Where would the top edge of the finished floor be?

UG 345.50, EG 348.50

Garage and basement then at the same level?

Yes.

Would that be an idea/well feasible?

Yes.

Of course quite a bit of earth would have to be moved

Yes. Here is a proposal without a cellar/basement with minimal earthworks: [ATTACH alt="Lageplan3.png" type="full"]41254[/ATTACH] You could also let the garage protrude into the planting area (exemption application with compensation proposals), so that there is still space for a carport next to it. Or rotate the garage 90° and set it into the slope. Perhaps one should also not close off the possibility to divide the property again in the distant future and build another building. Or, or, or,...

However, we only had the drawing or survey made after purchase.

The property is great. To make sure the house on it is great too and the overall concept fits, larger investments in planning are worthwhile.