Were the Gospel accounts corrupted as they were passed on? Was there any way to prevent this happening?

How big are the differences between the hand-written copies of the Gospels' accounts of Jesus? Do these undermine what we can know about…

Can we be confident that we have the original text of the Gospels? How does it compare to other ancient documents?

How many hand-written copies of the Gospel accounts are there? What does this reveal about possible mistakes?