Min Lon: 8
Max long:8
That is wrong. That would mean your scenery is 0 centimeters wide You can try something like this though (even smaller decimals will work):
Min lon: 8
Max lon:8.2
But they cannot be the same. I should add a check for that
Use the mapserver or MPMap to find the boundaries of the area that you'd like to generate.
So N47W008-N48W008 should I download,
E, not W. Germany is eastern of the Greenwhich, UK (which is W0 or E0, what you prefer).