I don't think TE has any Swedish members, at least I haven't noticed any that post regularly. I'm in Norway and may be the nearest one.
I haven't ridden Vättern myself but I have friends who have. I can ask them and see if they have any answers to your questions. I have the impression that it's a very friendly event.
Winter riding is much less about badassery and much more about bundle-uppery. - malkin
1995 Kona Cinder Cone commuterFrankenbike/Selle Italia SLR Lady Gel Flow
2008 white Nakamura Summit Custom mtb/Terry Falcon X
2000 Schwinn Fastback Comp road bike/Specialized Jett