I can’t follow the different ridge heights, the building area is almost flat.
Similar for us. Not in terms of eaves height, but roof pitch: in the south bungalows (explicitly mentioned), in the middle gable roofs and in the north cubic buildings (not two-story, but flat roof at a height of 7.80, single-story). Correct arrangement with regard to the optimal position of the sun across the entire building area.
how low the knee wall is with a ridge height of 4.50m and whether we might tend towards WA2 and a two-story house depending on that.
That depends on what you want or your needs. There is no information about that. We are two people and find it great to live in a single-story house.
If you dream of a gallery room, then an attic. If you are four people, then a townhouse of about 150-160 sqm fits quite well. Then the attic coziness is missing. If you want a vegetable garden, the garden’s footprint may well be larger. That again depends on whether one- or two-story. At 10 meters you get a tall house if you plan two stories with roof space. Etc. You cannot give a general recommendation for that. Both living sections hold their potential. For example also 10, 11, 14: lots of potential. Ultimately, you can build stylishly on any plot, even those orientations that may initially seem challenging.
One question currently occupying us is whether the southwest orientation of the first-mentioned lots leads to a terrace that is too hot in summer,
Yes, without an awning or shading it’s almost unbearable. Still always the favorite with standard floor plans (terrace by the large window areas). If I were to build again now, I would place a terrace in the NW. Still want most windows facing south as well as a terrace there. But that terrace can also be on the west side. It always depends on the floor plan; one does not exclude the other.
You asked the question in July: meanwhile I would have created “my house” for each plot. Have you done something similar for some plots?
would like to create a (small) vegetable garden with greenhouse, so I thought a southern orientation would be an advantage.
The southern orientation can also be at the plot corner in the east or west.
I advise you to sketch your ideas into various plots. Footprint of the house with terrace and entrance, two parking spaces with yard and driveway, as well as garden with greenhouse and small bed. That can be done in one evening. Then you will see the potential of each plot.