Dawn, I enjoyed your post. Let me bring a more historical/mythological perspective to bear on the topic....
In the ANE, the heavenly realm was pictured through a "like is like" principle. The Temple is thus a representation of the heavenly abode (see my recent post on the subject), and the "tent of meeting" ('whl mw'd) or Tabernacle used as the shrine of God ("El") in Shiloh (cf. Exodus 33:7-11; Numbers 11:16-29; 12:4-10; 2 Samuel 7:6; Psalm 78:60) is similarly representative of the "Tent of El" ('whl 'l) on the "mountain of assembly" (hr-mw'd) where the "council of El" (b'dt-'l) meets (KTU 1.1 iii 23-24; 1.2 i 13-40; 1.15 iii 17-19; Psalm 82:1, 6, 89:6-9; Isaiah 14:13; Ezekiel 28:2, 14). Later Jewish tradition in fact explicitly claimed that the Tabernacle was "copied from heaven" (Wisdom 9:8; 2 Baruch 4:3, 5; j. Berakot 4:5; Genesis Rabba 69:7), an idea which also finds expression in the NT (Hebrews 8:1-5, 9:24). Creating a facsimile of the heavenly abode on earth (whether on mountains or in high places or under trees, etc.) was thought to bring about a divine presence. The king was thought to be co-regent with the chief, ruling god ruling from heaven. The patron god appointed the king and the king received his power from the god (Assur or Shalman in the case of the Assyrian kings, Marduk or Nabu in the case of the Neo-Babylonian kings, Baal in the case of the Phonician and Canaanite kings, Chemosh in the case of the Moabite kings, Yahweh in the case of Judah, etc.). Each nation had its own patron god and conflicts on earth were viewed as reflections of conflicts in heaven between the tutelary gods vieing for supremacy. According to Deuteronomy 32:8-9, when "Elyon (=El) apportioned the nations, when he divided mankind, he fixed the boundaries of the peoples according to the number of the sons of God. Yahweh's portion was with his people, Jacob his share of inheritance". This text depicts El assigning one god to each nation and Yahweh inherits Israel as his own nation. Thus it is no coincidence that in Canaanite mythology, El had begotten seventy sons (KTU 1.4 vi 46) and Genesis 10 lists seventy nations, one nation for each god. When Judaism became monotheistic, this notion was adjusted so that each nation had their own guardian angel (cf. Daniel 10:13, 20, 21; 12:1; Sirach 17:17). Thus we read in the Targum Ps.-Jonathan that "when he [i.e. God] divided alphabets and tongues to the sons of men [at the Tower of Babel], he cast lots with 70 angels, the princes of the nations, who established the borders of the peoples." In this later tradition, Michael became the patron angel for Judah and eschatological Israel. But in the earlier period, the conflicts between Israel and the other nations were viewed as conflicts between Yahweh and the gods of these other nations. This is clearest in the conflict between Yahweh and Chemosh, which was realized in the earthly conflict between the Israelites and the Moabites. The old polytheistic notion of the different gods establishing the borders between the nations can be found in Judges 11:23-24 where Jephthah says:
"Now since Yahweh, the god of Israel, has driven the Amorites out before his people Israel, what right have you to take it over? Will you not take what your god Chemosh gives you? Likewise, whatever Yahweh our God has given us, we will possess." (Judges 11:23-24)
Thus when Moab is defeated in war, the Israelites say that "Chemosh goes into exile" (Jeremiah 48:7), while the Moabites viewed their own political fortunes as dictated by their god Chemosh as well: "Omri was the king of Israel, and he oppressed Moab for many days, for Chemosh was angry with his own land.... And Chemosh said to me , 'Go take Nebo from Israel!' And I went in the night and fought against it from break of dawn until noon, and I took it, and I killed its whole population ... and from there I took the vessels of Yahweh and hauled them before the face of Chemosh" (King Mesha Stele, COS 2.23, lines 5-6, 14-18). Moreover, when Israel "serves gods that were no part of their heritage" (Deuteronomy 29:24-27 ), Yahweh becomes jealous that "they have forsaken me and worshipped Ashtoreth the goddess of the Sidonians, Chemosh the god of the Moabites, and Molech the god of the Ammonites" (1 Kings 11:33), instead of following the god allotted to their nation. That is also why Ezekiel and the other prophets explain Israel's destruction by the Assyrians and Judah's destruction by the Babylonians as the result of their religious "apostasy" -- by turning to the gods of other nations, Yahweh abandoned his political support and left them defenseless to the forces of the Assyrians and Babylonians.
So the OT view of Yahweh is a direct reflection of political and social realities in the ANE. Just as the Israelite kings were ruthless against their enemies and fought against the Syrians, Moabites, Philistines, etc., so was Yahweh viewed as the divine warrior: "Who is this king of glory? Yahweh mighty and powerful, Yahweh the warrior!" (Psalm 24:8; cf. Exodus 15:3). Another archaic psalm declares that "the chariots of God are two thousand, thousands are the warriors of Yahweh" (Psalm 68:18). God was intimately involved in the affairs of man, fighting in their battles with his heavenly hosts. This theme directly appears in the Song of Deborah, quite possibly the oldest text in the Bible (dating to the 10th or 11th century BC), which refers to the stars as participants in the battle: "From the heavens the stars fought, from their stations they fought with Sisera" (Judges 5:20). Throughout the OT and in Jewish literature, we find that "stars" were synonymous with the "sons of God" and constituted "the host of heaven" (cf. Job 38:7; Psalm 147:4, 148:2-3; Isaiah 13:10; 14:12-13; 40:26; 1 Enoch 104:2, 6; cf. KTU 1.10 i 3-5 which through parallelism links the "sons of El" with "the assembly of the stars" and the "council of the heavens"), that is, Yahweh's military retinue. The sun and moon are also involved in earthly and divine battles according to Joshua 10:12-13, Isaiah 13:10 etc. So in short, Yahweh was viewed as king and warrior in the pre-exilic period and was believed to be intimately involved in the affairs of people. This idea also continued for some time in the post-exilic period, so by and large, the picture from the OT is a more "human" God, a "jealous" God (cf. Exodus 20:5, 34:14; Deuteronomy 4:24, 5:9, 6:15, 32:16, 21), who used pestilence and plague as weapons against his enemies (Habakkuk 3:5), who even sends forth false prophecy and lies if it would defeat his earthly enemies (cf. 1 Kings 22:19-23), and sends his prosecutor (called the Satan) in Job 1:6-13 to test his most faithful servants.
However in later Jewish tradition, God became more and more remote and the personalities of the council members become more and more distinct. In Zechariah 5:1-7, Joshua the high priest stands in judgment before not Yahweh per se, but the messenger of Yahweh (ml'k yhwh), and the Satan is standing at his right to accuse him. The significance of this passage is that the ml'k yhwh, not Yahweh himself (with the possible exception of v. 2, but cf. the Syriac which also has ml'k yhwh) who leads the council proceedings. Yahweh has become more transcendent, leaving his divine couriers to direct the assembly. As in Job 1:6-13, the Satan is not an evil being opposed to Yahweh but rather has the role of a prosecutor in the divine council. Yet such a prosecutor is not even explicitly mentioned in pre-exilic texts describing the divine council. What is most interesting is that in Job and Zechariah, stn occurs with the definite article showing that "Satan" was a title and not yet a proper name. Only in 1 Chronicles 21:1 do we finally see Satan appear as a proper name and as an adversary to Yahweh's plans. So Yahweh continues as the undisputed leader of the council, but more and more position and attention are given to members of the council. In post-OT material, however, Satan becomes viewed as the source and personification of evil, developing his own retinue of gods called "satans" (cf. 1 Enoch 40:7, 53:3, 54:6), and appears as the dualistic Belial or "Spirit of Wickedness" in Qumran, Mastemah "enmity, hostility" in Jubilees 10:8, 11:5, 11, 17:15, and the "Evil One", "Beliar", "Devil" or "Beelzebul" in the NT (cf. Matthew 4:1-11, 12:26, 13:38-39, 25:41; Mark 1:13; Luke 10:18, 11:18; John 8:44; Acts 5:3, 10:38, 13:10; Romans 16:20; 1 Corinthians 7:5; 2 Corinthians 2:11, 6:15, 11:14; 2 Thessalonians 2:9; Ephesians 6:11; 1 Timothy 1:20, 5:15; James 3:15, 4:7; 1 Peter 5:8; 1 John 3:8-10; Jude 1:9; Revelation 2:9-10; 12:9). The theological development of Satan as an all-evil adversary of an all-good God occurred through the influence of Persian dualism, which taught such a rigid division between good and evil, spirit and flesh, light and darkness, life and death. So while the OT view of Yahweh was that he controlled both the powers of evil and good, using evil for his divine purposes, in the NT and later Judaism Satan was viewed as the source of evil who lures the world away from worshipping God. The other members of the divine council also become more distinct, with the angels Michael and Gabriel being named in Daniel 10:13, 21, 12:1, with a hierarchy of angels governing the cosmos being presented in Jubilees 2:2, and the angels become viewed as mediators in 1 Enoch 99:3; Testament of Levi 3:5; Testament of Dan 6:2. 1 Enoch 20:1-8 names seven archangels and each is given a specific function. This hierarchy of angels replaces the older "council of Yahweh" and God is made more and more transcendent and remote, being relegated to "third heaven" (cf. 2 Enoch; 2 Corinthians 2:2), who can only be accessed through angelic mediators. These angels were further divided into different hierarchies of Good versus Evil (cf. Testament of Judah 20:1; 1QS 3:13-4:1), with a hierarchy of angels led by God and an opposing hierarchy of demons led by Satan the Devil. The difference between the Yahweh of the OT and the "God of Love" of the NT can partly be accounted for by recognizing that through post-exilic dualism Satan has absorbed all of God's "evil" qualities and through the principle of transcendence, God has become less and less like a reflection of humanity. Put another way, humanity has become less and less like a reflection of God (cf. Genesis 1:27; Psalm 8:5), with God more and more representing purity of goodness and man often representing the evil that comes from Satan. That is why the gnostics viewed the Yahweh of the OT as an "Evil God" because his actions were inconsistent with what they demanded from their "true God". But the OT Yahweh brought both good and evil, whether it was blessing the land with rain or "bringing evil" upon those who disobey him (cf. Joshua 23:15; 2 Samuel 12:11-14; Psalm 28:4).
So from my point of view, the move away from an anthropocentric and vengeful God to a transcendent and purely loving God in dualistic thought accounts for the quite radical change in God's personality between testaments.
