Each group has a couple of elders. They have the wisdom to allow the Holy Spirit to do that. . .and to discern when something 'foreign' has entered in. Elders from each group in the city gather together on a regular basis to share with the rest of the body what is happening in their fellowships, and to seek the mind of the Lord on strategic matters that might come up regarding the church as a whole. They also visit other home churches from time to time, both to check for correct doctrine and practices, and to see if the Holy Spirit is doing something that might be shared and brought back to their respective groups. They also get together to pray for those who need confession and healing.
Elders report to one another, and to apostles.
Oh yes. . Again, this is for the purpose of correction, communication, and impartation throughout the body of Christ. I forsee the possibility of a publication for each region. This publication would be the 'lifeline' of the fellowship of believers within a region, and will share timely prophetic words, teachings, psalms, parables, etc. Many would be drawn to the Lord through this work, which would be put together by those who are gifted for it.