Remove in Q2 (drywall) - possible?

If it's done poorly, yes.

We painted directly on drywall... beforehand we sanded the transitions a bit - but that already took half a week
Still, you can see quite a few flaws in the grazing light.

Paint: definitely prime first, then paint with regular wall paint.

Have you run out of money???

I don't understand the last question?! Where do I refer to costs or my available money? I believe one should rather not build a house if the money could even remotely run out before moving in?!

Q2 we are now after two coats of Stolevell fill plus fabric tape. Actually, I think it is good enough. My brother, a master painter, insists on a third coat of fine putty tomorrow evening. Then Sto Putzgrund without fleece will be applied, followed by Sto altweiss basic. He says that you will probably only find joints between panels upon very close inspection. And since I am not that picky, that’s okay. You can also putt endlessly.... Karsten

Not a primer, but stosil,fine.

so we have plaster on almost Q3. But you can still see the unevenness. Do yourself the favor and put on fleece wallpaper. You will just get annoyed. In the bathroom, I plastered and sanded. I think I did quite well and yet you can see it. Guests don't notice, but I do. Eventually, I'll forget about the bathroom. But in the living room, it will bother you.

We have filled ourselves with one pass and sanded once. Only in the living room did I do some touch-up filling in places. Then directly textured paint in two layers or wallpaper plus two layers of paint on top (beforehand, deep primer and white wallpaper primer underneath). You can't see anything anymore. And we are certainly no experts. I think what we have achieved should be Q2. I no longer see it so strictly. It worked so well throughout our whole house.

Roll plaster and woodchip wallpaper plus painting conceal extremely well. The same applies to fiberglass. Q2 is de facto finished woodchip wallpaper.