Is it possible to set the set/ control the pdf bookmark 'font-size' and 'Highlight current bookmark' state in a 'prince-pdf-open-action' or in another way?

Are there some kind of overview over the different PDF setting that can be controlled/modified?

Thanks
Martin

No, at the moment you can only specify whether the bookmark is open or closed by default, using the bookmark-state property.

There is a complete list of CSS properties Prince supports.