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

Were the Gospel accounts based on the testimony of eyewitnesses who were still alive when the Gospels were written?

This video describes the discovery of the earliest copy of part of John's Gospel, the 'John Rylands Fragment'.

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

Did Jesus claim or imply that he was anything more than a prophet? Or did his followers transform him into the Son of God many years later?

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?