Well, in Germany there is only one official language and that is German. If people from other countries come to Germany and they want to get the German citizenship, they need to speak German. But there are a lot of people who haven`t got citizenship and not all of them speak German - though that makes things hard for them, of course.
Ich möchte Deutsch (sprechen) lernen.
In Germany you speak usually the German language.
Does he speak German = Spricht er Deutsch
No she doesn't speak German.
How do you speak German = Wie spricht man Deutsch
They are German so they speak German to each other.
People in Vienna speak Viennese German.
No, sprechen means speak in German.
Does he speak German = Spricht er Deutsch
There are gnomes that speak German fluently because they are german. Or they simply studied it.
"Do you speak in German" is "Sprechen Sie Deutsch?" (formal) or "Sprichst du Deutsch?" (informal) in German.