You'd probably are already taken this forward but I would like to let here a small contribution for that discussion that was used for othe project:
Hope it helped somehow.I think that for the time being it will be best to create an association or a german e.V. since they could be good forms to host this.
Do not incorporate or host this in USA due to possible problems with software patents and arrassement and lawsuits that the project could suffer.
See the KDE e.V. http://www.kde.org/areas/kde-ev/
Contact: Matthias Kalle Dalheimer
See the Typo3 Association at http://association.typo3.org/index.php?id=t3a-faq
Contact: Robert Lemke
I think that Typo3 Association will be the best approach, but it is up to you.
You can dowload here the TYPO3 Association Statutes if you wish
For further information on the best system you can also contact htt://www.sovereigngroup.com and they may help you guys.