Sorry if this is a stupid question but I just upgraded to 0.94.1 from 0.93.3 (old Website) and had to rescan and rebuild Databases to make the programm pass the Step with reading the Header.
Yes, the database format has changed so it is both much faster to rebuild and rescan and much smaller than the original. You should delete the old databases to free up a lot of space (several 10s of GBs). If you delete the databases folder inside the data directory, it will remove the old databases and the new ones, but don't worry, the new ones will be rebuilt very quickly.Now it all works 
but I cant find any update function anymore... is it gone or is something at my programm wrong?
No, that is how it is supposed to be. The updater stuff was removed since the announcements server is no longer working, the development has changed leadership, no announcements server is set up that we can use, and we don't want any phone home code. It may be reintroduced later if we decide to. but I cant find any update function anymore... is it gone or is something at my programm wrong?