Painting works and putty qualities

Hello everyone,
I now have an offer from a local painter and need an evaluation:
I have to say that I have not yet had the opportunity to ask the company about individual details of the offer:

In general, we requested the following for our bungalow new build:

Execution of all putty work with plaster rails, priming, wallpaper, and white paint, and sealing of connection joints/transitions from wall to ceiling.

We wanted to be offered a medium-grain woodchip wallpaper, painted white, and alternatively white painted fleece wallpaper:

Offered or used materials:

Putty:
StoLevell in Fill
Ardex 828

Woodchip:
StoEuro Trend medium,
Metylan TG/Power,

Fleece:
StoTap Pro 500,
StoTex Coll,

Paints:
StoColor Opticryl Matt;

Connection joints/transitions
Sista F130

The offer is structured so that he applies Q2 putty and then Q3, and then depending on what we decide, he glues and paints either woodchip or fleece wallpaper.

I have the following questions about that:

The walls are covered with Fermacell by the house builder:

Is the Sto material suitable for Fermacell, or does he need special material for that, meaning do these products work together?

Do I have to apply Q3 putty for woodchip wallpaper necessarily? The price difference between woodchip + Q2 + Q3 and fleece + Q2 + Q3 is so small that it does not make sense to use woodchip then. It's only about €300 difference.

Regarding Q2 and Q3, did he just not bother to break down the work better? Or was he thinking along the lines of applying Q3 directly, so that if it is ever renovated and fleece ends up being applied, Q3 is already done?

Wtf...why do you want to wallpaper Q3 with woodchip or fleece?

You can wallpaper woodchip directly onto the concrete ceiling elements after the joints have been filled!

Either you have too much money or you want to torture the painter.

Sorry, but I only know it from hearsay that for woodchip wallpaper at least Q2 filling is required and for fleece fiber at least Q3. It is said that if no wallpaper is applied and it is only painted, a minimum of Q4 is needed. However, this refers to drywall, which is why the question arises if it looks different with Fermacell?

My painter said that for [Raufaser] (classic, not fine), Q2 is sufficient, for [Vliestapeten] good Q3 or Q4, because otherwise every unevenness will be visible there.

My painter said that for textured wallpaper (classic, not fine), Q2 is sufficient, for non-woven wallpapers good Q3 or Q4, because otherwise you see every unevenness there.

He is right. If you want smooth walls, and therefore Q3, I would always use painter’s fleece, without it the walls quickly look bad. We have a comparison here directly with our neighbors, with us using fleece, next door without, same company for the plaster. After almost 2 years there is still no crack to be seen with us, next door after a few months the first of many, looks unpleasant.

Q2 putty is ready for wallpapering. Q3 is for fleece. Q4 would be something for Millimeterhermänner. Sto levell fill-in is good. Ardex too. Why use Optycryl as a coating and not Stobasic? Optycryl is a kind of latex and completely unnecessary in many areas. Basic is a good dispersion paint. Fermacell or Rigips, the filler doesn't care.