Land planning - which house type/size is most sensible?

I also see the driveway more in the east...

I thought so at first, too. Not a problem with one car. With two, the house itself shifts quite far to the west. How many cars are desired here was not mentioned. So, for now, I assume two. With such small plots, one could also consider a basement and plan less area for the house. It's a question of money.

The orientation is the point of every floor plan discussion

Yes, I noticed that.

I was rather looking for one where the advantages of certain orientations are possibly explained in more detail. Like why which room should ideally be placed in which cardinal direction.

I had the same at first. No problem with 1 car. With 2 cars, the house itself shifts quite a bit to the west. How many cars are desired here was not mentioned. Therefore, I am assuming 2 for now. With such small plots, one could also consider a basement and plan less area for the house. It's a question of money.

We have 2 cars, but would also park one on the street or one behind the other if it helps with space.

I don't want a basement at all

How can I, as a layperson, tell where the building boundary is or whether boundary construction next to the neighbor is allowed?

Your development plan contains no building boundaries and building lines. From this it follows initially that the statutory boundary distance - in most state building codes 3 m - forms your effective building window. And there is an "o" for "open construction" in it - this means that you must observe this boundary distance on all sides. However, garages are usually allowed to abut the boundaries: single garages without extensions practically almost always, only in individual cases is it "more complicated".

Your plot thus practically provides a building field in the form of a roughly 11.20m x 16.30m rectangle. Your example floor space of a square 10.11m, translated into the same area of a rectangle, would have about 8.40m x 12.20m roughly the same aspect ratio as this building window. Simply put, a "square" here only results in garden on the east and west sides and otherwise just a fence and plaster path, whereas a "rectangle" also allows a significant south garden.

My favorite is also a rectangle with at least a knee wall from 2m.

The popular delusion among laypeople that a knee wall must be built up as high as possible to the eaves line is practically a royal road to a spatial impression that is neither fish nor fowl in terms of an "attic". It is often forgotten that this height line is practically also a dividing line for windows: on the eaves side, only roof windows above, only facade windows below, or as a third option dormers everywhere you want to avoid this decision. I consider sensible knee walls to lie around 120 (+/- 30) cm above finished floor level.

I was rather looking for one where the advantages for certain orientations might be explained more precisely. So why which room should ideally be placed in which cardinal direction

The sun rises in the east, it follows its course in the south, it will set in the west, in the north it is never visible. Starting from a day shift worker: morning sun for bedrooms and bathroom, southwest provides pupils with daylight for their homework, and a maximum northwest is still good for sunbathing during dinner. Rooms with small windows (utility room, guest WC) and the pantry are happy to face north.

Your development plan contains no building boundaries and building lines. From this it follows initially that the legal boundary distance - in most state building codes 3 m - constitutes your effective building area.

Isn't the dashed line on the development plan a building boundary? At least that's how it is described in the legend, right?

The popular delusion among laypeople that the knee wall must be built as high as possible, up to the hat string level, is almost a royal road to a spatial feeling that is neither fish nor fowl in the sense of an "attic." It is often forgotten that this height line is practically also a dividing line for windows: on the eaves side, only roof windows above it, only facade windows below it, or as a third way dormer windows everywhere one wants to avoid this decision. I consider sensible knee walls to be around 120 (+/- 30) cm above the finished floor level.

Delusions or not, personally I much prefer a knee wall about 2 m or higher. Yes, one must be aware that on the eaves side this affects the windows. However, on the one hand there is also the gable side, on the other hand depending on the room there are also nice window solutions for the case. Currently I live in a maisonette condominium with a knee wall of about 1.40 m. I no longer want the sloping ceilings. Not so “low.” For me, the gain in room height and more flexible placement options outweighs it. Besides, I like best the combination of a high knee wall with a shallow roof pitch. If you can then forgo the few square meters of attic and leave it open to above. That’s how it will be with us. Everyone has to decide for themselves, but you can also look at and compare both options in a show home park to see which suits you better.

When I look at the photo, a height difference is particularly noticeable towards the northeast corner of the property (based on the height of the street or the house in the east). The hedge appears as if it is planted on a slope seen from the street. It is difficult to estimate from the picture, but I suspect about 1m? Do you have more precise information? If parking spaces/carport are arranged in the northeast, this must be taken into account. If it is more than 1.5-2m, a (partial) basement with parking spaces under the house would be advisable? In any case, I would try to ensure that the terrace of the house is not below the height of the sidewalk, otherwise people walking by can easily look onto the terrace and into the living room.