A&D: Which decisions will be made by the whole membership?

As few as possible – ideally none. Some organizations keep some domains as part of the whole membership when transitioning into sociocracy, for example, major changes in governance. Yet, ideally, the mission circle and the general circle as well as finance have clear domains in circles that take ownership of those decisions. In some places, an all-member meeting can be used to select a member representative to the board
That said, there can still be a place for all-member meetings that might not be decision-making meetings. For example, circles might ask for feedback for policies that are in the works, there can be intentional spaces for exploration and connection among the membership, or training for everyone on relevant topics.

For more information, check out our handbook Many Voices One Song section 2.2