Question on traffic rules

Hello people I’ve been on the lookout for ages, but so far nobody has been able to give me a real (safe) answer. So I try it here, even if I don’t know exactly if it’s the right forum…(so forgive me if it’s the wrong one) 1.: can you overtake vehicles on thick dashed lines (like an autobahn ascent) on the right? 2.: I regularly argue with buddies about whether to put the turn signal before entering the roundabout. like, as long as you drive the first one out again? (provided the first exit is not directly opposite, but rather about 90° angle or less) Thanks already for your answers! You would end many discussions sometimes