How many empty conduits are advisable when constructing the floor slab?

Yes and no, in the other thread I was actually primarily concerned with the functionality regarding the house entry.

Here the question of sizing arose for me. Whether KG pipe or multi-utility pipe would initially be a secondary question. See examples in the first post, cistern/pump. Or are such things relevant in a different construction phase, just like power cables leading outside to the terrace/garden shed/gate/carport.

That with the house entry it is *only* about the supply, everything else is realized in a different way (which one?).... drilling through the outer wall (in the base area), or .....

Then open another one and ask there preferably about the length of the pipes... And in another one then how high they need to protrude from the screed...

Depends on how you plan. I would do everything together at once. There are also multi-duct installations. In any case, a seal must be applied from the outside as well. If it is already backfilled, you can dig it up again... 100 mm pipes are quite large. For electricity, garden water, telecom... 40 mm pipes are more than enough. Just google "multi-duct". They come in X combinations. Surely there is something for you too. As I said, I would do it all at once and guide the empty conduits out of the base area. Later, you can simply dig further wherever you need and pull the cables through.

1. Wastewater
2. Water
3. Electricity and telecommunications / fiber optic (yes, alternating current can interfere with lines - then choose a separate route)
4. Service water e.g. cistern

4-split multi-sector is the standard size, costs €600.. they are not incorrectly set.

Where can you get them at this price? I assume that is gross.