re: religious blocks, I think a diplomatic bonus/malus for same/differing religion à la EU4 would be sufficient. While religious blocks "worked" together at points (e.g., Catholics for the first Crusades), it don't find it necessary that all people of same religion would have to get along well (which surely they didn't in history) nor that different religions make alliances impossible, as cross-religious alliances/partnerships existed relatively often, even between Reformed/Protestants and Catholics in the "religious" reformation wars (France and the Protestant League) and between Catholics and Muslims (e.g., France and Ottomans). Well, maybe the France examples just show that their result-oriented diplomats valued other things higher than religion...