Comprehension question about construction costs

Very thanks already! That helps me to better classify this rough estimate. I have already included the outdoor facilities in my Excel, as well as a double garage. Not that I have much hope for a plot of land, but the ideal area would be in the greater HN area; so not exactly a cheap place. Besides the land costs, I had the following items on the list: house costs with those ominous 2k (or calculated with 2.1k) for 150 sqm, of which 10% GU/architect, 50,000 € incidental construction costs, 20,000 € kitchen, 25,000 € buffer, 40,000 € double garage, 70,000 € basement (depending on the plot = slope as (partial) living area, which would be included in the 150 sqm), 20,000 outdoor facilities (probably too little). And I was just not sure what is already included in the rough estimate. Everything added on top of that quickly adds up to a considerable amount.

Are the bathroom fittings (excluding bathroom furniture) and underfloor heating included in the 2000 or are those extra? So I know how big the depression will be

Included in the standard. Golden faucets or a walk-in shower can cause additional costs.

of which 10% GU/architect

The general contractor takes nothing. The 2000/sqm is a flat rate for a standard calculation for building a house at standard level with a general contractor without painting work. As of 2019. The north-south gradient is not calculated.
The architect according to HOAI costs quite a bit more.

Thank you very much for your clarification as well! I think with that I can roughly estimate the required budget.