The current system is more like the proposal 2 diagram, in that the Board is directly selected by a general election to serve for a set term, and holds general meetings publicly.

I think all of the systems have merit, and think they would all likely serve the community about equally well. I would prefer something where the general electorate have a direct vote in the leadership of the e.V. directors. In the end, the simplest model will likely be the best one, since the more complex it gets, the harder it becomes to implement (and the more arguments spawn over interpretation).

I also see no problem asking for some minimal support (say 5€/year) but note that requiring such for other actions (voting rights, etc) could become a technical challenge itself. Making other systems reliant on tracking that could be tricky to pull off, especially for existing systems not setup for it (like voting).