Ha, this thread needs to placed into a zBrush wiki! If there is once something like that.
I found my last problems.
First the tiling wich is not done when Apply Displacement is used - export-import trick.
Second, in Displacement mode everything lost it’s sharp corners from my low poly - then I saw that “Quick display” is turned off by switching “mode” on.
Reason - if quick is turned off there are smoothing options to adjust under “Display Properties”.
Or klick “Quick” on again, then everything has sharp corners again but looses its displacement.
I remember michalis once told us this “turn quick off” trick to render Sculptris sculpts in zbrush smoothly without any retopo 
Just if it’s not said already??
Speaking for me about your selling plans:
If I am testing around and have free tools like yours, I am fine. If I need this for a job and it’s below 30$, it’s bought without even thinking.
I try to support guys like you. Badking has this huge library of free zBrush stuff I used a lot - no question that I donated him.
Michael Dunham offering his very useful brushes for free at the beginning (and still does offering most free) donated for sure.
Another question if you don’t mind.
Using Element 3D, there is no displacement. So only way to use your stuff as a bump isn’t it?
Thank you so much.