As that is one of the main areas of work of Ecobytes, providing free/libre tools and related workflows to (disperse) teams and networks, it would definitely be an interesting focus, also for us.
Sure, there are mattresses, although not 20-30. I would check in the next house meeting how we could think this. Would you all like to sleep directly in the house, very tight, or is it ok and desired to also look for places around (WGs, Yurt and caravans, etc.)?
There is a Essensverschenkregal at the entrance of TT, but it's quite small and busy at all times (so not to expect a lot). There is a lot of people containering, which is why in Witzenhausen itself it is difficult to find good containers. Usually Bad Sooden (15 km from here) had quite good containers, but I heard last week they fenced it hard.
However, there is a good scene for this (see e.g. http://containerprozesswiz.blogsport.de/), and I think we could use your event to mobilize/create a momentum with the community.
There are many fruit trees around, but I guess by November most are out of season, apart maybe from some late apple trees. Transition Town Witzenhausen has active work on this (harvesting abandoned orchards, finding owners who are willing to share, etc.), so we could possibly use it. But, again, November will be limited in the amount supplied, and people here (remember, it's a faculty of ecological agriculture) are already very good in getting hold of available resources.
Furthermore, we can also ask the local CSA initiative to provide some vegetables and potatoes. In any case, there is twice a week some surplus left, which can be taken by anyone. We could ask if it would be ok to offer this to you directly. Again, it's November, so vegetable production will be very low in comparison to now.
Please clarify the desired length with your group. Also, it would be important to understand how you want to contribute to the house, especially as you are probably not paying a contribution. This can be in the form of renovation of maintenance works, organisation of events generating income (e.g. cooking, cafés, etc.). The house is passing through a quite critical situation (although improving), both in terms of finances and collaborators, so it would be very important to see how your stay could contribute to improve the dynamics.
I would need to bring ideas to the Transition House assembly, ideally already for the one next week. Or I ask the people to express what they would like to have from you, and we initiate dialogue.
For the hackerspace (3rd floor of the house), which is directly rented by Ecobytes, we obviously provide you with the space unconditionally, so the request above is only for the usage of the remaining hous.
Looking forward for the yunity bunch to come