Finally!
After spending hours and hours on watching tutorials and trying to apply them on my image there now is a result I like to share with you: my first image processed off the scratch with PixInsight! (Same dataset as before)
Slowly I have the feeling to "get a leg on the ground" and establish some kind of workflow within that truly complex and "arbitrary" Imaging SW.
Just very minor finishing steps in AffinityPhoto.
CS, Martin