Your recent questions would all be excellent ones to ask the two attorneys who will be speaking at the MARA Conference next weekend.  Maybe if you get answers from them, you can share them with us here on the forum.  Meanwhile, I believe that as a statutory association you are not required to file - the contractors are responsible for filing.  If you were a non-profit, that might be different, but I am not involved with a non-profit so I couldn't tell you how that would work.  Perhaps someone else can address that.