Which heating system is currently the best?

Oh, it's not that complicated at all. With 35 degrees flow temperature, you can manage that perfectly.

Then bear fur and red wine, as well as an open fireplace, woah. But I found a 48-hour combat troop training of the BW in the Bavarian Forest at minus 30°C more romantic.

No, a fireplace is not my thing. It makes too much work and dirt.
-30 are only a few days in a row on the highway romantic...

Can you still use screws or nails with a wall heating system? What is the wall structure like in such a case?

Can you still use screws or nails with a wall heating system? What is the wall structure like in such a case?

You can google the structure of a wall heating system. It's actually quite simple and similar to underfloor heating. The heating loops go on the unplastered wall, then reinforcement mesh and plaster over it.
If you want to hang a picture, you should be careful where you drive the nail...

Hello,

Is it possible to use screws or nails with a wall heating system?

Firstly, hopefully, you wouldn't get the idea to drill into a floor heating system. Secondly, why would you want to diminish the purpose of the wall heating system by hanging pictures/cupboards in front of it?

Kind regards