Financing land and house? Taking out a mortgage? Construction costs?

I ALSO FIND SOME THINGS ABSURD!
Insanity, do some people really have to show off here?

I am happy and grateful for any meaningful advice. But I can well do without insinuations.

The deep foundation of the property has already been carried out, a final site plan is available including an expert report. Based on this, a bill of quantities was created, which was discussed with the structural builder.
Of course, there can still be additional costs here, but that is what the buffer is for.
There may be additional costs, but no more surprises regarding the ground. And a disposal/dumping is probably out of the question for the reasons stated.

Now don't all start criticizing the fact that an architect is involved in the planning. There aren't only architects for residential buildings, and even such an architect can miscalculate. For us, the very first estimate from the architect and the final invoice from the civil engineer for earthworks and ground slabs differed by a factor of 3. When we gave the "go" for the project, we were then aware of that and also of the risks related to soil conditions (geological survey) and the steep slope location. We planned an additional 15% on top and also needed it because instead of an excavator, a chisel was required in some places for the graywacke.

Well, that overlapped with the post from the Bavarian woman. Before that, you were safe. It was anyway against the "Architektenkritiker".

I ALSO FIND SOME THINGS ABSURD!
Unbelievable, do some people have to show off here?

I am glad and thankful for every meaningful hint. But I can well do without insinuations.

The deep foundation of the property has already been done, a final site grading plan is available including an expert report. Based on this, a bill of quantities was created, which was discussed with the shell construction company.
Sure, additional costs may still arise here, but there is now a buffer for that.
There may be additional costs, but no more surprises regarding the soil. And a removal/disposal is probably not necessary for the reasons mentioned.

And now?! You’re going to make a list and shove it under your husband’s nose?! You both wanted this special equipment!!!! Otherwise, off to the general contractor, he should calculate.

The deep foundation of the property has already been completed, a final site grading plan is available including an expert report. Based on this, a bill of quantities was created and discussed with the shell builder.

This information was missing. Therefore, there cannot be a five-figure surprise regarding any item, and you have buffers for all the four-figure surprise items like more steel required due to structural reasons or general material price increases, etc. Then everything is fine.... apparently and you are back in budget, right?

This information was missing. So there can’t be a five-figure surprise regarding any position, and you have a buffer for all the four-figure surprise items like more steel needed due to statics or general material price increases, etc.

Then everything is fine.... apparently, and you are back on budget, right?

I hope so at least, the buffer is now about 10% of the construction sum. It went quite smoothly and on good terms “just on top.”
Still, it’s crazy how expensive everything is...