The Internet is a mess as it relates to this topic. Dogmatic biblical lessons abound about the justice and kindness of ancient figures who may never have existed; conspiracy theories lace the results, involving reptile people and the Illuminati planting ancient Israeli archeological finds and giving instruction to Israelite kings; it's all a giant shitshow and I can't tell where I should be looking.
Just about the only clear, concise, seemingly-accurate summary of the events of this period as they pertain to Judaism itself is Evid3nc3's "A History of God (A)", which covers the Canaanite pantheon, the origins of its myths in neighboring cultures, the reign of King Josiah and the Deuteronomic reforms as a response to Assyrian weakness, and the development of the monolatristic cult of Yahweh into monotheistic Judaism as a natural continuation of that polytheistic Canaanite religion. He covers the authors J, E, and P, and the multitude of edits to the Bible in-depth in his other videos.
However, he seems to make assumptions. Apparently, the only evidence of the existence of King Josiah is the Bible itself; while the Deuteronomic reforms seem to line up as a foundation for the overthrow of Assyrian rule, names and figures are a little vague.
I want the realest information I can get. No dogma, no conspiracies. Just what we absolutely know. Who were the Canaanites? Who wrote the Bible, and why? What did these peoples' religion look like at every stage of development? What was the political atmosphere of the Middle East at the time? What holes still need to be filled?
Is this information centralized somewhere? Are there any good books I can purchase from Amazon? I want to know!
The Internet is a mess as it relates to this topic.
Yes. It is. Even the YouTube video you linked is not really accurate, nor does it do justice to the subject matter or the many/various subtleties and nuances that are part and parcel of higher biblical criticism.
I'll first encourage you to check out episode 18 of the AskHistorian podcast. I cover a lot of things but it's a handy starting place.
Apparently, the only evidence of the existence of King Josiah is the Bible itself; while the Deuteronomic reforms seem to line up as a foundation for the overthrow of Assyrian rule, names and figures are a little vague.
There's really no reason to doubt the historicity of Josiah as an historical personage. We have external evidence in the Taylor Prism that Hezekiah existed--and Josiah was his descendant.
That's also not why Deuteronomy was written. I'd suggest setting aside that video and forgetting most everything in it. Whoever made it is not a scholar nor are they an expert on the material with which they claim to deal in the video.
Really, the questions you're asking require book length answers (i.e., for each individual question).
A few resources you'll want to check out:
A. Faust, Israel's Ethnogenesis: Settlement, Interaction, Expansion and Resistance (Equinox, 2006).
I. Finkelstein, A. Mazar, B. Schmidt, The Quest for Historical Israel: Debating Archaeology and the History of Early Israel. Atlanta: Society of Biblical Literature, 2007.
E. J. van der Steen, “A New Model,” in Idem, Tribes and Territories in Transition (Peeters, 2004) 295-310.
C. A. Rollston, Writing and Literacy in the World of Ancient Israel: Epigraphic Evidence from the Iron Age (Atlanta: SBL, 2010).
D. M. Master, "State Formation Theory and the Kingdom of Ancient Israel," JNES 60 (2001) 117-31.
L. Grabbe, A History of the Jews and Judaism in the Second Temple Period, vol. 1 (T&T Clark, 2004) 22-68, 132-364.
S. L. Sanders, The Invention of Hebrew (Urbana and Chicago: University of Illinois Press, 2009).
E. Nicholson. The Pentateuch in the Twentieth Century: The Legacy of Julius Wellhausen (Oxford, 1998)
T. B. Dozeman and K. Schmid, eds., A Farewell to the Yahwist? The Composition of the Pentateuch in Recent European Interpretation (SBLSymp 34; Atlanta: SBL, 2006), 1-129.
A. de Pury and T Römer, "Deuteronomistic Historiography: History of Research and Debated Issues,” in Israel Constructs its History: Deuteronomistic Historiography in Recent Research, edited by A. de Pury, T. Römer, J. D. Macchi (T&T Clark, 2000), 24-141.
U. Becker, "Die Wiederentdeckung des Prophetenbuches." BTZ 21 (2004), 30-60.
S. Mowinckel, The Psalms in Israel’s Worship (Biblical Resource Series; Eerdmans: Grand Rapids, Mich., 2004 [1962]), 1-41.
J. L. Crenshaw, Old Testament Wisdom: An Introduction (3rd ed.; Louisville: WJKP, 2010), 4-21.
I. Kalimi, “History, Historiography, Historical Evaluation, And Credibility— Chronicles In Its Context,” Journal of Hebrew Scriptures 6 (2006) 40-66, http://www.arts.ualberta.ca/JHS/Articles/article_52.pdf
J. Trebolle Barrera, The Jewish Bible and the Christian Bible: An Introduction to the History of the Bible (trans. by Wilfred G. E. Watson; Leiden: Brill and Grand Rapids: Eerdmans, 1998).
M. Fishbane, Biblical Interpretation in Ancient Israel (Oxford: Clarendon, 1985), 1-32, 66-88, 98-123, 131- 137, 281-300, 307-314, 320-350, 410-411, and 435-440.
B. A. Nakhai, Archaeology and Religions of Canaan and Israel (Boston: ASOR, 2001).
B. D. Sommer, The Bodies of God and the World of Ancient Israel (Cambridge, 2009).
Z. Zevit, The Religions of Ancient Israel: A Synthesis of Parallactic Approaches (London: Continuum, 2001).
J. Hutton, “Isaiah 51:9-11 and the Rhetorical Appropriation and Subversion of Hostile Theologies,” in JBL 126 (2007), 271-303.
J. Bottéro, Mesopotamia: Writing, Reasoning, and the Gods (Chicago: University of Chicago Press, 1992).
M. van de Mieroop, A History of the Ancient Near East, second edition (Oxford: Blackwell, 2007).
B. E. Shafer, ed., Religion in Ancient Egypt: Gods, Myths, and Personal Practice (Ithaca: Cornell University Press, 1991).
J. J. Collins, Between Athens and Jerusalem: Jewish Identity in the Hellenistic Diaspora (second edition; Eerdmans, 2000)
C. E. Fonrobert and Martin S. Jaffee eds., The Cambridge Companion to the Talmud and Rabbinic Literature. (Cambridge: Cambridge University Press, 2007).
M. Jaffee, Early Judaism (Upper Saddle River, N.J.: Prentice Hall, 1997).
S. W. Crawford, Rewriting Scripture in Second Temple Times (Grand Rapids: Eerdmans, 2008). – 149pp.
J. J. Collins, Beyond the Qumran Community: The Sectarian Movement of the Dead Sea Scrolls (Grand Rapids: Wm. B. Eerdmans, 2009).
DO NOT rely on A History of God by Karen Armstrong. She is not an academic. She is not a scholar. She writes popular literature and is not trained to treat this data in a professional manner.