your first question, my source is the 34 different versions bibles ive read. and studied, some over a few hundred years old. spoiler alert, there are vast differences even among the same kind of bible. depending on its age.
the second thing you mention, is infact the 4 gospels detailing his life and ministry, but the are not his works. they are from his apostles, from their views. don't worry they are starting to dig up a lot of the work specifically from joshuas perspectives, and teachings. I'm sure in next few years if church deams it wont disbar their versions of things too much will release it for you to read.
your third question. the greatest source is common sense. and the ability to understand from the perpectives beyond onself, and ones time. to understand how all things are the same. and how only perspective, and the words to describe them change. also over a thousand technological creations exist from the specific examples from the books in the bible. like the creation of modified food, space ships, power cells, excetera.
also I feel like this post was made to get your opinions, not question anothers.