Thanks for your answer!
I sorted out the fullscreen problem by simply using the latest Debian image. Somehow I got an old one.

I had some closer looks into the Debian image and found that you've been credited in the .xbindkeysrc file. So I guess you have some experience with the input challenges. Any thoughts on my mouse click emulation idea? Do you think it is reasonable or might it conflict with something else?
I'll try to get something working during the weekend and will post the results.

I've also noticed that there are some key combinations with shift+mod5. Do these actually work? I can't see any effect, but this might as well be due to my problems pushing two keys with one finger or the qwertz layout ouf my keyboard (which is a total mess in the terminal, I'm trying to get a qwerty keyboard).