What were German submarines in the two World Wars commonly called?

A German-born printer named Louis Prang introduced which holiday cards to the U.S. in 1875? Which German master wrote the autobiography "Poetry and Truth", begun in 1811? A German geology professor makes a subterranean expedition in which 1864 classic by Jules Verne? Which German river gives its name to wine grown on its banks? A German woman may pluck her "Augenbrauen". What are they? A gerontocracy is a government ruled by whom? A G.I. Joe figure introduced in 2000 represents one of which Native American World War II code talkers? A giant Ferris wheel graces which city's Prater park, opened to the public by Emperor Joseph II in 1766?