We probably need to beat the Yahwist-Mazdaist Connection into the ground and come up with some coherent answers. I confess to not having a whole lot in the way of cites for this; it’s been a long time since I studied into it in any depth.
First, dispose of the “God’s Consort” thing that Scott Plaid raises. “El” was, effectively, Central Semitic for “god” – note the lowercase. To a certain but quite real extent, the Canaanites were syncretic – your El, who lives on top of nearby inaccessible mountain and controls the thunder, is a different manifestation of my El, who lives in the clouds and sends the rain, both of whom are also their El, who is responsible for the fecundity of the flocks. Some of these Els were parts of henotheisms: the sole god of our city, the only one properly worshipped here, though we certainly won’t deny the god they worship over in your city either. Others were dei otiosi, the creator god who then left control of the happenings of the world to other gods; or the supreme god of a pantheon. Els who were male principles or Zeus-counterparts tended to have a consort, usually called Asherah or something very similar (Astarte and Ashtoreth are variations on the theme).
With the advent of the Israelites and YHWH-worship, things changed. There was but the one god, albeit other nations worshipped other gods, who may or may not have been “real” in the conceptions of the people of the times, but who were emphatically not to be worshiped by those who followed YHWH. The monotheistic and henotheistic Els were equated to YHWH, who picked up an archaic plural form of El, Elohim, as His particular epithet. (His name is YHWH; his title is Elohim, God par excellence.) And He emphatically did not have a consort; any other gods were there at His sufferance, either subordinate deities existing at His whim, demons tempting the sinful Canaanites, or pure and simple figments of their imagination.
So El Shaddai, El Berith, and the rest, portrayed in Genesis and elsewhere in Scripture as epithets for YHWH, are in origin local tutelary henotheistic deities which were assimilated into the growing conception of YHWH as sole and supreme God.
Now, one peculiar phenomenon in Genesis in particular, and to a lesser extent throughout the Torah and the older stratum of Biblical literature, is that God and His messengers are conflated. God (not God-and-two-angels) visits Abraham at Mamre under the guise of three men (seen by Christians of fulfilled-prophecy or typological bents as being a type of the Trinity), and then two of those men, now termed messengers (malakim, or aggeloi, i.e., “angels”) head over to check out Sodom. But in the Mamre account they’re not termed angels; they’re 2/3 of the manifestation of God. Likewise, it’s not clear whether Jacob wrestles with God or with an angel; both explanations are implied. And in particular, in the frame story for Job and the sparse patristic accounts of the Satan, he is regarded as a sort of cosmic Ken Starr – part prosecuting attorney, part anti-sin investigative task force, and part tempter to sin, by way of testing the righteous. God is regarded as a sort of cosmic potentate, whose messengers do not speak for themselves but in His voice, with the Satan as a part of that court in that servant-of-God-but-antagonist-to-man capacity.
Anything produced during or after the Exile, however, has a much more defined system. God is clearly distinct from His angels, who now come in a heirarchy, and the Satan, from being a Special Prosecutor, has moved into a role of rebel against God and supreme agent of evil. But this is precisely the imagery associated with Zoroastrian cosmology: the good god Ahura Mazda is warred against by the equal-but-lesser Angra Mainyu, both of whom have their coteries of potent angelic figures who are distinct and independent from them.
In short, Judaism absorbed the dualistic metaphysics of Mazdaism and incorporated it into a stringent thoroughgoing monotheism by having YHWH served by angels, separate created beings who are His messengers, some of whom rebelled under the Satan and are bent on causing evil to happen.
It’s a massive sea-change from the one-supernatural-entity-worth-mentioning YHWHism that had preceded it.
However, I disagree with the following: