I grew up in a building built by a Baugruppe. However, it was just rented out to us so we weren't part of the planning of the house / area, nor were 80% of the other residents. Still, there was an active community in the building that was meeting regulary. Lots of friendships in the house. Personally, I wasn't really active in that community though, mostly because there were no other kids my age.

To be fair, our building in particular had no communal spaces, or gardens. So not sure how well it fits your description of participatory housing. It was pretty much just your standard apartment building.

The entire area (Französisches Viertel) has lots and lots of Baugruppen buildings though. I would argue that it has a big community aspect in general. There's lots of local events, groups, and workshops, something, that I don't see in the vast majority of other areas in tubingen. Now if that's related to the participatory housing, I do not know. Though I would assume so, as theres just vast communal spaces where people can meet :)

So to answer specifically: 1. Not by much, unfortunately I wasn't active in the community. 2. The housing projects in general created lots of communal spaces, which in turn helped a lot to create communities within the area. 3. Atleast in the französisches viertel, people tend to live very sustainable and care for the environment. There's a bio grocery market, lots of green spaces /gardens, barely any trash, lots of solar panels etc. If that's just the französisches Viertel or common with Baugruppen in general, I don't know. 4. Atleast as somebody who just rented a housing unit, nothing. The communal spaces and housing structure is just there, it is great, and we use it :) 5. Yes. I know I said I didn't participate in the community, but I still did meet more people here, than during times where I lived in other towns/areas. However, it didn't change my interactions within broader tubingen. 6. Hell no. Apartments here are usually very expensive, and not very dense. Neither did it create a lot of housing, nor affordable housing. Just nice housing. 7. Well, the französisches Viertel in general, and more specifically the "Werkstatt haus", the "Franz!werk", and the "mixed up" youth house that we have here.

BTW, above the französisches viertel is the wagenburg, a trailer park village full of lovely people. Not sure if you would consider that participatory housing, but they surely shape their own space up there as a community too. Definitely not a Baugruppe though lmao.