I know he played more wing for Leverkusen, Dortmund has all sorts of wingers so I think he's played more inside lately. His natural position would probably be left sided winger or AM.
Maybe so. But they've seemingly been playing well with those two. Perhaps not defensively though, perhaps they don't care about that as much.
Where would Brandt play if Can is in there?
He may not even play that much in Dortmund. Seems like Brandt and Witsel will be the starters. Then Can will want to move again once they sign Camavinga.