Basement insulation interior wall new construction

No. 1 does perimeter insulation 100mm all around. Plus 80mm under the sole.
No. 2 wants to do internal insulation 100mm around and under the basement hallway.
No. 3 only mentions something about wall insulation 5mm bitumen boards.
No. 4 gives double bitumen coating as insulation.

Intuitively, I would also choose in your order (and the 4th "insulation" is probably a really bad joke, because bitumen coating maybe protects against water, but not much against heat loss). Exterior insulation / perimeter insulation is preferable in my opinion. You can also do 150mm to achieve a better U-value. However, it's also a matter of money then.

Yes, we see it similarly. Unfortunately, we have little idea of a price range (or rather, we are kept in the dark about the price per sqm). Of course, the GU can present us with astronomical prices if we confront him with a perimeter insulation. We will definitely have quite a few points to discuss.

See my post #16 Completely wrong order that you are following there. 1) Energy consultant (or whoever carries out this task) prepares the preliminary thermal insulation certificate. This includes insulation thicknesses and qualities, which are agreed upon with you and the architect. 2) Architect prepares the bill of quantities/tender using the insulation thicknesses and qualities determined in 1) 3) Structural engineer / general contractors submit comparable offers based on 2)