Floor plan revision, tips and experiences for improvement?

What would the solution be then? Place the house completely at the bottom, forgo the view, and then be able to access the garden from the back of the upper floor? Then the garage driveway is basically level, but there is no light at the back in the basement either

That's how we have it. Basement towards the garden side is underground and towards the street at street level, garage at street level and from above as a balcony at the dining room and from there around the corner of the house as a terrace into the garden with another access from a hallway. I personally like that very much. We have a nice view from the balcony above the garage and from the dining room (also from the kitchen if there were no house in the way) and at the same time ground-level access to the garden and from the basement out. This results in the disadvantage of steps up to the front door (in our case only 8 or 9, since the front door side is higher than the garage side). In our case there is also an upper floor and an attic. However, our house is an old building with different requirements for the basement than would be the case if one wanted to use it as living space. And we have so much slope that something like this is practically mandatory.

My wife absolutely wants a connection between garage and house,

"Better halves" are not necessarily always wiser. In a dozen years with half a kilometer of walking distance between garage and house (no envy, it’s not the same property), I can count on one hand how many times I got wet on that path. I once sketched how I would place the buildings. Next to the garage, I left space for garbage bins, and otherwise ported the garage in the same format. I made the house one meter wider with the same floor area and left it with the lower left corner of the plan in the same position for easier comparison. Widened by one and a half meters, it would even be possible to save a whole meter of area, and thereby create a 20 cm height difference between the uphill and downhill eaves sides at a 20% slope:

If you absolutely want to climb high because of the view. Then maybe like this.

"Better halves" are not necessarily always smarter. In a dozen years with half a kilometer on foot between the garage and the house (no envy, it is not the same property) I can count on one hand how often I got wet on this way.

I once sketched how I would place the buildings. Next to the garage I left space for garbage bins, and otherwise ported the garage with the same dimensions. I made the house one meter wider but with the same footprint and left it in the same position with the lower-left corner of the plan for easier comparison. One and a half meters wider, you could even save a whole meter with the same footprint, and thus at 20% slope have 20 cm height difference between the uphill and downhill eaves sides:

Thank you very much for the effort. May I also ask how it would be sensible to realize a forecourt so that ground-level parking spaces can be reached.

Path to the house then with stairs or is the house located low enough?

Consider that with the terrace you are sitting on a silver platter.

I like the suggestion from 11ant with the separation.

I would always try to have an access without steps, also to the garden behind the house, for hand trucks and the like.

This house would have the garage arranged crosswise, but then three floors, of which the middle one at the back is level with the garden. Can I also implement this with two floors, because then there also has to be space for technology in the house. Sleeping downstairs will be difficult, however, because everything at the back must then be in a basement without windows.

In addition, there would even be an access to the house.

Picture 3 can work well. Adjustments to reduce costs are in my opinion necessary. I will take a closer look at it.

But then you have 2 floors up to the living area. As already indicated, my suggestion would rather be living downstairs.

Save costs by a smaller house. With 150m2 you can also plan well. 50m2 *3000 euros are 150k that you need for a double garage and slope.

Are there already any information about the building ground? Have you asked the neighbors if there is rock? Why did the previous owner back out?