Building an end terraced house - Which technical requirements should be considered?

With a mono-pitched roof up to 15 degrees and a gable roof up to 40 degrees:
That will indeed be difficult if you can't come to an agreement.

Is there actually a set site plan here?
The B-plan link has been deleted.

Does that then mean with the 2.5-story gable roof that the street-facing side only has the two full stories WITHOUT the roof

There are no 0.5 stories...

It is probably without the roof, as I have seen in the setback calculations of some designs, where only the outer wall was taken as a reference.

with the mono-pitched roof, which is fully built up to the top, the actual total height?

The mono-pitched roof will presumably open towards the garden, so the "lower" outer wall facing the front garden counts here as well.

With a monopitch roof up to 15 degrees and a gable roof up to 40 degrees: That will indeed be difficult if you cannot agree.

2:1 - it will then be a gable roof. According to the building authority, it must be uniform.

As far as I do not remember imprecisely, I believe it is like this: up to a certain roof pitch, the eaves height / wall height alone counts; for the setback floor, however, it usually limits the "excess" wall height it creates already at its own setback, so that practically only the wall height of the full floors counts as the actual basis for setback areas.

As far as I do not remember imprecisely, I believe it is as follows: up to a certain roof pitch, the eaves height / wall height alone counts; in the case of a setback floor, it usually limits the "extra" wall height it creates already on its own setback, so that practically only the wall height of the full floors is counted as the real basis for distance calculations.

I can well imagine that here the roof pitch of 45 degrees is the limit for the calculation.

We are about to meet with the other new neighbors. Conveniently, the revised offer from the general contractor just arrived, reducing the foundation costs from about €9,800 to €3,000 due to the basement request from the middle house neighbors. Let's see how they react to that.

It would also be interesting to know what you think about the following prices:

Painting work including materials (Q2 including textured wallpaper and one coat of paint) including sanding and filling of ceilings and walls: €4,850 plus VAT.
Painter's fleece on walls on the ground floor excluding stairwell, hallway including Q3 substrate: €1,650.00 plus VAT (what will happen with the ceiling?)
Laminate and vinyl work including materials with all ancillary work such as sanding and filling: €6,100 plus VAT.

Laminate and vinyl cover about 120 sqm. Currently, about 45 sqm of vinyl (material calculated at €33/sqm) is planned, with the rest in laminate (material calculated at €25/sqm).

For the painting work, one can calculate with 145 sqm for the entire house.

Is it even worth doing it yourself or having another company do it? I find the prices very fair.

Let's see how the conversation goes later – especially regarding the costs for the foundation.

You are. I wasn't even there at the founding and already with flooring... a bit early, I would say!