As there were some questions regarding the German DVD release: They don't have this info on their website but according to amazon.de the audio will be German and English as well as the subtitles.
The set is still not available but they're working hard to release it as soon as possible.
Thanks to Andreas for the information.
Some other people asked me about the box set. Just to clarify: You order the complete season but it's packed in two boxes (as there's not enough space for 7 DVDs in one box).