Turks everywhere? You must have been in the west. In the eastern parts of Germany the bigger towns will have a FEW Turks (enough to run the Doner Kapab shops...) but that's it. Even in Dresden (a million or so people) I did not see one mosque, and I'm not sure these Turks have Islam as much more than a tradition to them... It's definitely not a potential "Eurabia" at least in the east.
A major difference between eastern and western are the numbers of immigrants. The economy is so bad in eastern Germany even the Turks don't want to live there.
Yes. West of the Rhine. I can't speak for the east nor other places I wasn't.
Maybe the East's miserable economy is a mixed blessing?