House planning with 3 children's rooms on a 473 sqm plot

The first direction is not specified. Possibly place the long side facing north, so there is more space....

That depends on where you want to have the garden? In the S?

How big do you want to build? Lichthaus 152 has 163 m2.

Is the land included in the 700 k?

the plot costs about €100k, leaving €600k for the rest. We are planning with 160-170 sqm. If the floor plan is efficient, you might save a few sqm. Currently, we have 120 sqm with a basement. We are missing a room. We are torn about the garden. To the south is the access road, and you might feel a bit exposed. If the house is set further forward, you just have shade...

In search of floor plans we came across the following topic. Floor plan That already looks very efficient at the top at least.

???

[*]A maximum wall height (WH) of the main buildings of 6.5 m on the mountain-side plots and 5.5 m on the valley-side plots in relation to the respective access road is permitted according to the usage template. The lower reference point is the street level in the middle of the outer property boundaries along the street front. The upper reference point of the fixed wall height is the intersection of the exterior wall of the building with the roof covering.

Unfortunately, I really can’t make sense of that below right now.

What don’t you understand by that? According to the photo – actually a decent slope – you are on the valley side. (Note, I am not familiar with the development plan!)

the slope is about 5% if those are contour lines in the plan excerpt.

I am also interested in what the development plan says.

According to the excerpt from the development plan, you can build 2 floors.