Hi again ;-) I'm happy I finally found how to render fonts, this should definitely be documented somewhere with all necessary steps.
On rendering wrapped text I found an inconsistency:
When you choose to tell pySDL2 a max width for the wrapped text so it can be wrapped, pySDL2 forgets about the background color.
This is, because the called function TTF_RenderUTF8_Blended_Wrapped, which is called 'if width' doesn't take background colors, only the font color. (files: font.py and SDL_ttf.h).
I think there are two possible solutions:
a) document this behaviour
b) build a rectangle of the desired background color behind the wrapped text