I would appreciate it if you would explain a little more what you would consider a "definite act whereby one side has excommunicated the other in total". I suppose if you are thinking of this in terms of the Orthodox saying "All Roman Catholics now living and their generations yet to come are cut off from the bosom of the Church", or vice versa, you may not find such a definite declaration towards one or the other group. However, Vatican I's anathema against those who deny its papal dogmas, various Orthodox anathemas against Roman Catholic teachings, and other such things, while perhaps not explicitly naming groups in question, clearly intend to exclude them, I would think. If you could elabourate on this, I think it would be helpful.
I thought your point 2 was interesting, but there is a problem with it, I think. Judas by his actions left the apostolic college. Matthias, by the choice of the Holy Spirit and the apostles, replaced him. So I can see, to an extent, the point you are trying to make by citing Revelation. But I don't think that prevents an apostolic church (for this conversation's sake, I trust we are referring to those churches which can legitimately claim foundation by one of the Twelve) from "leaving" that communion, and others from "entering" that communion through the will of God and the action of the successors of the apostles.
The passage from Ezekiel which you cite in point 5, as I understand it, refers primarily to personal sin. While schism and heresy are certainly sins, they are sins with effects outside the sphere of the actual persons involved. The sins of heretics and schismatics affect those who unwittingly come after them, "born into" those heresies and schisms, as well as affecting those who never left, having preserved the true faith. Those who have come after cannot be held accountable for those who came before; nevertheless, they are affected by their actions.
Regarding your second point 5 (which I will call 6
), it assumes that everyone who calls himself a Christian is part of the Body of Christ. Is this really the case? If so, then there really are no differences between us, and the current situation we find ourselves in is silly. If, however, it is possible that not everyone calling himself Christian is part of the Body of Christ, then what is the criterion for determining who is and who is not "in"?