Are the decisions of the Council binding on the whole Church?

Answer:

No. The decisions cannot be considerd binding for several reasons:

1. First of all, not all Orthodox Churches will be present, so decisions taken in their absence certainly cannot be considered binding on them, unless their own Holy Synods adopt the decisions of the Council.
2. Secondly, even if all Orthodox Churches were present at the Council, the decisions would not be binding unless and until the Holy Synods, the hierarchy, of each Local Church met and adopted them.
3. Thirdly, since the Council is not inviting all Orthodox Bishops, but only 24 from each Local Church, the decisions of the Council cannot be considered binding unless all of those bishops - a majority of the heirarchy of the Church (about 3/4ths of the hierarchy!) - who were not invited also accept the decisions.
4. Finally, Met. John (Zizioulas) of Pergamon, of the Ecumenical Patriarchate has written that a bishop who has not been invited to the Council is not bound by its decisions and can freely and rightly reject them (See: the periodical Θεολογία, 2014).

ALSO, IT IS ESSENTIAL TO NOTE:

• All decisions contrary to sound Orthodox theology and ecclesiology are likewise not-binding, irrespective of whether or not they are ratified by the Synod of a particular Local Church or group of them.