Erandir,
sounds like you have a mate that questions like mine. I've come to realize that no answer would really satisfy. But,
As far as the letters be sent to congregations goes; I would ask who sent the letters?
Paul was out in the missionary work, on his own, writing letters to the congregations that he started.
-who did paul consult with before writing letters?
-who did paul say taught him everything he needed to know
-how does paul speak about the leaders of the jerusalem church (Gal. 2)
The one letter that the Jerusalem council sent wasn't sent by just the council, it was sent by: (Acts 15:22,23) "Then the apostles and presbyters, in agreement with the whole church, decided to choose representatives and to send them to Antioch with Paul and Barnabas. The ones chosen were Judas, who was called Barsabbas, and Silas, leaders among the brothers. 2 3 This is the letter delivered by them: "The apostles and the presbyters, your brothers, to the brothers in Antioch, Syria, and Cilicia of Gentile origin: greetings. "
-who sent it? Just small governing body of apostles? older men? whole congregation?
-who received it? every congregation? every christian? specific locale? christians with specific background?
Your other point was about the association of brothers being so large that control is needed for unity.
-what truly is unity?
- is there a difference between conformity and unity? what? does it matter?
-Jesus is the head of the organization. Is he not capable of handling matters whether there is 1 or 100million chrisitans?
-What unity does the bible actually speak of?
-Who is actually responsible for saving anyone? (1 example: Ephesians 2:8-10)
I know this won't answer everything someone brings up and maybe some of it just doesn't make sense to anyone but me, but I hope it helps if the conversation every comes up again. This board is where I learned to ponder these things and try to apply some real logic to my bible study (alright no joking - I'm still learning).
Good luck.