Also, another favor. Since I haven't been at Vulkan, can you update it's course page? E.i., exact map coordinates, course description, etc...? That'd be fantastic. Thanks for your help and reviews!
That's a question I can't answer with 100% certainty. Most people will set up stands at bigger events (German Tour B-Tiers or A-Tiers). You can find the German Tour events here:
As for permanent shops...you would have to find Crosslap or Discmania workers. Honestly the only shop I can think of is in the basement of the clubhouse in Söhnstetten, and even there I'm not sure what it's operating hours are.