Postwar Germany had a lot of financial and practical aid from the Marshall Plan. Also, the Germans still had enough of a work ethic to rebuild and create in West Germany during 1949-1956 an "economic miracle." Even East Germany had the highest standard of living among the Communist Bloc.
Do Germans today still have that work ethic? I don't know. But they seem to have been ravaged by liberalism, let alone Islam.
Yes they do. They have the largest economy in the E.U.