Attach to property access planning

Is the carpenter here perhaps the gatekeeper at the bottleneck "approval planning" and buying the basement too?

I thought so, that an "ambitious" timber builder is planning.

I would look for an architect, be open to solid brick construction, plan the carport below. House possibly without a basement. The basement here will soon have as much earthworks as on a flat plot.
The garage/carport roof could possibly be used as a south-facing terrace.

Have you already thought about how the outdoor area should look?

A fundamental question. Have you already signed with the wood house builder or can you still change?

The garage seems to me, according to A6, either to have to be integrated into the house or only be able to stand separately if this still occurs within the building window (or on one side also as a boundary garage)

I love clear formulations in development plans. You are probably right, but taken literally, A6 could have been omitted except for the last sentence. Only with the addition of the word "only" does the first sentence make sense in my opinion, because as it stands, its statement is obvious. The same applies to the third sentence. According to §23, para. 5 of the Land Use Ordinance, garages could also be permitted. The text was probably written by a psychologist who absolutely wanted to avoid negative formulations. He did not succeed with the last sentence, which, however, is the only one that contains a useful statement, unfortunately invalidating my (#19) and also the last suggestion of the original poster (#24).

Not for me, because the system section in each case also represents built-in garages.

... but not on the mountain side at the level of the basement. A 50% incline and the existing wall height limitation exclude an integrated garage.

The solution I have in mind is as I have already drawn it

Apart from the violation of the pb taboo zone, your proposal does not solve the height problem. You have to overcome a 4m height difference up to the house; your parking area manages a maximum of 15%, which corresponds to about 1m. For the floor plan, you always have to design at least one section with existing and planned terrain through the middle of the house so you can roughly estimate how much you have to excavate and whether the development plan can be complied with.

Catching the slope with concrete and placing a wooden house on it is a common standard. You don’t have to make any compromises there. I can report this from experience. Also, when it comes to the driveway, you can make it a bit steeper – when winter comes, you just have to park at the bottom if necessary. However, you have to calculate at least 35m of driveway length if you want to comfortably drive into a garage and also park the car in front of it. We have a driveway that many people consider too steep and overcome 10.5 meters of elevation over nearly 100 meters from street level to the parking lot.

... but not on the uphill side at the level of the basement. 50% slope and existing wall height restrictions exclude an integrated garage.

The system section here in post #17 and more clearly visible at clearly shows an integrated garage on the uphill side as well, but only at half the slope.

Counteracting the slope with concrete and placing a wooden house on top is a common standard. [...] when winter comes, you just have to park below if necessary.

I mainly see only outdoor parking spaces here. And if I understand the original poster correctly, the general contractor does not want to start deeper because, as a timber construction general contractor, he only wants to buy the basement and not also the first residential floor above it.