Building plot in a pit, neighbors are situated higher

I would definitely raise the property to street level. Possibly higher at the back as well. Construction is happening everywhere. You should be able to find free material for filling. Then cover layer with topsoil. Otherwise, you will always have the issue of drainage and landslides. Even if this would be the responsibility of the party causing it.

I would definitely raise the plot to street level. Possibly higher at the back as well. There's construction everywhere, so you should be able to find free material for filling. Then top layer with topsoil. Otherwise, you'll always have issues with drainage and landslides, even though that would be the responsibility of the person causing it.

Filling at the back sounds good, but would you then build a basement? We would like to plan without a basement.

You have to build on the property.
A basement is probably useful here. Under the house, better compaction is needed than in the garden…
Get a good architect and have him make some proposals.

The dashed line is the building envelope?

Is the garage or carport allowed to be built outside the building envelope?

Is the dashed line the building envelope? Is the garage or carport allowed to be built outside the building envelope?

Yes, exactly, the garage may be built outside.

we have received a commitment from the municipality and now have to make a final decision.

So you did apply for it after all!? Why doesn't one inquire about buildability in parallel with the "reservation"? You can "get something out of" (almost) every plot and build it optimally, only effort and costs can vary greatly.