A lot of the noise problem was due to improper grounding, which was my fault, but thanks to the patience of the people on this forum, I managed to solve that and many other issues.

I was considering to run the limit swithes on 24v or at least 12v, but they seem to work fine, from the low voltage perspective. They however are very cheap lever switches and tend to have some parts wobble or come loose. I will upgrade to some profesional ones soon in the future.

My workshop is right next to the high voltage power lines. Like 3 meters away. The building existed before the high voltage tower was put in place. I asked a few guys at the City Hall about this issue, but they do not seem to have a problem or an interest in that.

I.m a bit concerned about some aspects of the cnc build, but not afraid. Crashing it, does not seem a big deal in theory, with single drive for each axis.
And it would not be the first time I mess up something in this project. Doing the math, I think I spent around 2500 euro for this project until this point. I bought the components bit by bit, during a few years, with the intent of building it someday. But from this amount, 5-600 euros was the tax for stupidity, representing materials or components, which from lack or knowledge or impatience etc, I ruined. But for the experince aquired, it worth every penny. :)

What I am somewhat afraid, is that, in order to reach a certain profitability with this kind of machine, you need a decent cutting speed, and I might not be able to get that properly. Perhaps I should have bought higher quality components, and make the cnc smaller and lighter. Who knows. I have a few components left from this build so maybe in the future I.ll build a smaller version.