(1) While it is true that the documents were copied by hand, it is my understanding that when the canonical books were agreed upon (by Iraneus, I believe), less time had passed than you indicate, and there was a process of comparing various scripts to find which was to be accepted. (2) The bit about the vinegar is a matter of interpretation, not of actually changing the text itself. From what I understand, there is currently a good deal of ferment about the role of Mary Magdalen. None of it involves source material; it involves interpretations made centuries later.
Knesset approves 2015-16 state budget in first reading (Haaretz)
from the article: Benedict at Auschwitz: unanswered questions