They are 17 Hippies, though there were only 12 in Adelaide. These pictures are from a workshop session on the Monday.
Their music is a mixture of folk, pop and many other styles. They did more songs in French than German - apparently actually starting to write songs in German was a bit of a breakthrough for the group. I gather from what I remember of the program, and the English bits on their site, that they set out to make their own 'Berlin style'. During the workshop they tried to explain the importance/improbability of using the German language, but I don't think we really got it. Made me curious though.
Their bandleader talked a bit about the hand signals they use when improvising. They've been playing together for many years and do this pretty effortlessly.