Slight slope - Should you fill or build on the slope?

The house would then be far away from the street, right?

Yes, the relocation of the utilities would then become more expensive. However, I do not know what costs per meter would then be incurred for the respective connection.

The front door would be approximately 12m from the street.

Avoiding a basement is, in my opinion, not a value in itself. Therefore, I also think it is not worth incurring either basement-price-high costs for earthworks, slope protections, and drainage or even placing the house in a spot where one could do something nicer with the property. I also would not want to unnecessarily trade a soccer field for driveway paving.

I will now have the architect explain to me exactly what is possible here. I definitely do not want to avoid a basement either, for example. If the basement should cost 5,000 more than the excavation work, then of course I will take the basement, especially since it can create even more storage or living space.

We had already chosen the house. The dimensions of the house are 9.5m x 9.5m. It is a prefabricated house, [...] We already have an architect,

Why a prefabricated house if you have an architect – is it at least a custom design; or do you mean by architect a plan drafter from the manufacturer who merely inserts the individually ordered knee wall height into a standard house model?