The questions were clarified after a call to the hotline - thanks digitec!

The holder has an adjustable foot as shown in the photo.

If the monitors have VESA mounts, yes.

A) The bar is 90cm high from the desk top, so the top screen centre can be placed at maybe 2 centimetres less height because of the bracket. B) The bracket on the pole is a clamp fixed with an Allen screw. Although the necessary Allen key is kept in a holder on the stand itself, I would say that it is neither quick nor practical to adjust the height regularly because you can't really reach it from the front. C) Yes. My second 27" screen on the stand is relatively high up and clearly tilted forward, the whole thing doesn't wobble a bit when I shake it and doesn't show any other tendency to want to tilt.

No, the holder has a foot.

I will respond in English, but hope it will be helpful for you. Firstly - check this video out: https://www.youtube.com/watch?v=T4zpQvGg8rs Dual 49 is possible, but it is not simple. I have 27 on the top + 49 on the bottom and to fix 49 I had to put immense pressure on the bolt....It holds, but it is not designed for this weight ))

I have two 34" 21:9 monitors on this arm. I can't answer the payload, but the thing is very stable. I wouldn't mind hanging 20-25kg on it.

I have a 32" monitor mounted on the bottom and an iiyama 22" monitor on the top. The lower monitor is not tilted and is mounted about 7cm from the base. The upper monitor is tilted down by about 30° and there is about 10cm of remaining rod at the top. Without promising you anything, I would say that - depending on the angle of inclination - this could work. It could be that the maximum size specification refers to TWO monitors of this size.

No, it supports a maximum of 32".