Is there a link between El and Elohim of Genesis 1 and do you believe the Creation account there is based on Canaanite mythology?
Well, 'lhym is a distinct Israelite term for God that probably dates after the merger of El and Yahweh, tho it has its origins as a term for the divine assembly (cf. the Eloim in the Phonecian creation myth of Philo of Byblos, who are described as the allies of El/Kronos), although 'lym is more common in this sense (cf. Ugaritic 'lm "gods" and 'lym in Exodus 15:11, Deuteronomy 32:43, Job 41:25, 1QM 1:11, 1QH 7:28, etc.) and bny 'lym and bny (h)-'lhym even more so (cf. Genesis 6:2-3, Job 1:6, 2:1, Psalm 29:1, 89:6, etc.). Even though El has been conflated with Yahweh in most of the OT, we still see an especial relationship between the divine council and El in the language that is used; hence, the bny 'lhym are kwkby bqr "morning stars" in Job 38:7, which corresponds to the kwkby 'l "stars of El" in Isaiah 14:12, and the hr mw'd "mountain of assembly" in the same verse evokes the 'dt 'l "assembly of El" in Psalm 82:1 and the hr 'lhym "mountain of the gods" of Ezekiel 28:16. All of this has a Canaanite foundation, as the bn 'il "sons of El" are referred to as the 'dt bn 'ilm "assembly of the sons of El", the 'dt 'ilm "assembly of the gods", the pchr m'd "council of the assembly", and the pchr kkbm "council of the stars" in Ugaritic texts (cf. KTU 1.4.III.14, 1.2.I.14-16, 1.15.II.7, 11, etc.), and the council is convened by El at the gr 'il "mountain of El" (KTU 1.2.I.14). Of course, this is related to the broader ANE belief that the gods are gathered in a council on a cosmic mountain (cf. Mount Olympus in the case of Greek mythology, Mount Hermon in Ugaritic mythology, and also cf. 1 Enoch 6:6, which depicts the fallen angels as gathered together on Mount Hermon, and the reference to the Shaddai-gods forming a mw`d "council" in the 8th century BC Book of Balaam son of Beor Inscription).
The Priestly creation narrative in Genesis 1 is a late reformulation of ideas found in Psalm 104 and other sources, toning down some of the more overt mythological themes found in the poetic literature (such as the conquering of the sea/deep in Psalm 104:6-8, which is expressed more fully in the combat myth of Job 26:12-13, Psalm 89:9-10, Isaiah 27:1, 51:9-10, Baba Batra 74b, cf. Enuma Elish, COS 1.111, IV.93-130, KTU 1.2.IV.19-34, 1.5.I.1-4, Hesiod, Theogony 820, etc.). The plural "us" of Genesis 1:26 however is an echo of the older idea of the divine assembly, mentioned more overtly in Job 38:7: "Where were you when I laid the earth's foundation ... while the morning stars sang together and the sons of God shouted for joy". The Deutero-Isaiah portrayal of creation is markedly different by depicting Yahweh as alone: "I am Yahweh, who made all things, who alone stretched out the heavens, when I spread out the earth, who was with me?" (Isaiah 44:24). This may have been a deliberate response to the Priestly creation account, as there are many other counterpoints in this section of Deutero-Isaiah (cf. Isaiah 40:18, 46:5 on Yahweh not having an "image" or "likeness" as implied in Genesis 1:26, Isaiah 45:7, 18 on Yahweh not creating the earth a waste and having darkness precede light as in Genesis 1:2, Isaiah 40:48 on Yahweh not growing tired or weary as implied in Genesis 2:2-3, the rhetorical question in Isaiah 40:41 that implies a failure to understand how the earth was founded, etc.). Although the Priestly narrative has 'lhym in view instead of 'l "El" as the creator, there is a vestige of the older Canaanite tradition in the non-Priestly narrative in ch. 14, which uses the old Canaanite epithet 'l `lywn qnh shmym h-'rts "El-Elyon, creator of heavens and earth," a designation elsewhere attested in variant form in extrabiblical ANE sources (e.g. the 12th century BC Hittite DN Ilkunirsha < 'l qn 'rs "El, creator of the earth", 'l qn 'rts "El, creator of the earth" in the 8th century BC Karatepe Inscription, ]qn 'rts in an 8th century BC Jerusalem ostracon, 'lqwnr` in the first century AD Palmyra Inscription, b`shmyn qnh dy r` in the Hatra Inscription, 'l qn 'rts in the second century AD Leptis Magna Inscription, etc.). The other main primitive El text outside of the Balaam traditions in Numbers (which utilize Shaddai and El as DNs, cf. "He hears the word of El, he sees what Shaddai makes him see" in Numbers 24:3-4) is the Blessing of Jacob in Genesis 49:24b-26:
"By the hands of the Bull of Jacob ('byr y`qb, cf. 'l y`qb "El of Jacob" in Psalm 146:5-6 and tr 'il "Bull El" in Canaanite texts, e.g. KTU 1.1.III.5, tr 'il 'ab "Bull El, your Father"), by the name of the shepherd, the Rock of Israel, by El your Father ('l 'byk) who helps you, by El Shaddai ('l shdy) who blesses you, with the blessings of heaven above, with the blessings of the Deep (thwm) crouching beneath, with the blessings of Breast and Womb (shdym w-rchm, cf. shdy "Shaddai" in the OT and Asherah and Rahmay/Womb, consorts of El, in KTU 1.23.R.12-13). The blessings of your Father are mighty, the blessings of the mountains of the Eternal One, the bounties of the hills of Olam ('wlm, cf. 'l 'wlm "El Olam" in Genesis 21:22, Psalm 90:1-3, etc., El as the 'b shnm "father of years" in KTU 1.2.III.5, the El-like `tyq ywmyn "ancient of days" of Daniel 7:9)".
So there is a considerable imprint of older traditions in the henotheistic scheme of the OT.
I have also found other suggestions of polytheism in ancient Israel, such as Josephus writing about Abram. that "he was the first man to publish the notion that there was but one God, the Creator of the universe." (Antiquities Bk.1 Ch VII.1) This would certainly suggest that before Abram other gods were worshiped apart from YHWH wouldn't it?
Well, Josephus is rather late and mostly interprets received biblical traditions (cf. Joshua 24:2 and the midrashic Abraham legends in Jubilees 12:1-14, Pseudo-Philo 6:1-18), and the patriarchal traditions in Genesis themselves construct a history of Yahwism that is probably more ideological than historical. In reality, polytheism and henotheism defined the religion of Israel and Judah throughout the pre-exilic period, peppered with rather brief reforms like those of Hezekiah and Josiah, as the Deuteronomistic History relates in polemical fashion. It is not until Deutero-Isaiah where we find true montheism.
And what about the Teraphim, which I believe were Semetic house-gods?
The references are rather obscure, but yes, these are relevant. More relevant to the monarchical period are the many references to Israelite iconism in the Deuteronomistic History, such as the asherim and the baalim, the Nehushtan, the masseboth, the golden bulls of Jeroboam, etc. etc.
We know from the Hebrew Scriptures they were tollerated by Jacob and his descendants right up until the time of King Josiah and probably later. It seems then that a polytheistic belief was nothing new to the Israelites then was it?
It wasn't merely "tolerated", it was Israelite religion, it was what any observer would have seen in Israel or Judah, it was state-sponsored and official, apart from the few reformist kings and prophets who pressed for an aniconic and exclusive Yahwism. Even that tho is not true monotheism....monolatrous Yahwism did not deny that other gods exist, it only demanded that Yahweh alone be worshipped.
In looking at the Greek Scriptures afresh, I haven't as yet, come accross an instance where Jesus ever refers to himself as the "Son of God," but on numerous occasions he refers to himself as the "Son of Man," which suggests to me that he was emphasising his motality. What did the title "Son of Man" mean?
In the gospels, there are TWO distinct usages of the expression "son of man". One is the typical non-titular use of it simply meaning "man". For instance, Mark 2:27-28 says that "the sabbath was made for man, not man for the sabbath, so the son of man is the lord of the sabbath". This passage does not portray Jesus as claiming to be a unique "lord of the sabbath", it simply means that the needs of man have precedence over the demands of the sabbath, i.e. the sabbath isn't the lord of man and may be "broken" if life is at stake. But there are other "son of man" passages in the gospels that have a distinct apocalyptic character; they portray a "Son of Man" as eschatological judge who comes on the clouds of heaven, with great power, accompanied with the angels, who sits on the throne of glory, who executes judgment, etc. (cf. Matthew 10:23, 13:41, 16:27-28, 19:28, 24:27-44, 25:31, Mark 8:38, 13:26, 14:62, etc.), and Jesus is portrayed as using this eschatological title as a self-descriptor (e.g. Mark 8:31, 9:9-12, 14:41). This title is based on an exegesis of Daniel 7:13-14, where "one like a son of man" is not yet a title but introduces the motifs of coming/arrival, judgment, clouds, glory, etc. It was however developed into a messianic title in the pre-Christian (Essene?) Book of Parables of 1 Enoch, written in the first century AD, and this text is something like a missing link between Daniel and the NT usage of the title (e.g. "He sat on the throne of his glory, and all judgment was given to the Son of Man", 1 Enoch 69:27; compare Matthew 25:31 and John 5:22).