congratulation zouzi !
same as me, got an invitation.
this is in hamburg for GU test(general undergrund). and the psycho test are the same as skytest
http://www.skytest.de/english/index.php?page=shop/index.php with a passrate close of 1%.
then I think there is a sim test later with a passrate of 0.5%.
as my chances are close to 0.25%, I would like to know if they pay for accommodation and transport to hamburg cuz I don'have lot of cash for video games.