I use the Enoch online at http://www.ccel.org/c/charles/otpseudepig/enoch/ENOCH_1.HTM
but at home I use this one http://www.amazon.com/gp/product/096757370X/ref=cm_rdp_product_img
Genesis 6 is really plain about what happened, though redacted in it’s inforamtion, the Hebrew states that ben elohim took wives of bath Adam -sons of God took wives of daughters of Adam, both before and after the flood.
The big difference between Charlesworth's and most sources is the scholarly approach to the material at hand. His does not have a theological predisposition at all.
I have seen nothing to compare with Charlesworth's collection of ancient manuscripts, exhaustive research and footnotes - though I am not familiar with Ronald K. Brown - your second source.
On the second point, Enoch reveals that the ben Elohim ("sons of God") in Genesis 6 are angels who were sent by God to look after banished Adamic men. The angels taught men all kinds of things they were not supposed to know, including weapons and warfare, adornments and such. And they bred with the female offspring of Adamic men producing ravenous giants.
All of those angels who bred with women and produced giants are chained in darkness until the judgment. They were not on earth after the Flood - and are not out there now - breeding and making more giants.
For if God spared not the angels that sinned, but cast [them] down to hell, and delivered [them] into chains of darkness, to be reserved unto judgment; - 2 Peter 2:4
As I recall, their offspring, the giants physically died in the Noah flood but their spirits survived until the judgment. These are the demons, for instance:
Of course the scholars exclude theology as "fact" on principle ("methodological naturalism") and thus lean to a comet explanation. However, they have no explanation for the destruction happening simultaneously, world-wide.
At some time around 2300 BC, give or take a century or two, a large number of the major civilisations of the world collapsed, simultaneously it seems. The Akkadian Empire in Mesopotamia, the Old Kingdom in Egypt, the Early Bronze Age civilisation in Israel, Anatolia and Greece, as well as the Indus Valley civilisation in India, the Hilmand civilisation in Afghanistan and the Hongshan Culture in China - the first urban civilisations in the world - all fell into ruin at more or less the same time. Why?
Some decades ago, the hunt for clues passed largely into the hands of natural scientists. Concentrating on the earlier set of Bronze Age collapses, researchers began to find a range of evidence that suggested that natural causes rather than human actions, may have been initially responsible. There began to be talk of climate change, volcanic activity, and earthquakes - and some of this material has now found its way into standard historical accounts of the period.
Agreement, however, there has never been. Some researchers favoured one type of natural cause, others favoured another, and the problem remained that no single explanation appeared to account for all the evidence .
The hunt for natural causes for these human disasters began when the Frenchman Claude Schaeffer, one of the leading archaeologists of his time, published his book Stratigraphie Comparee et Chronologie LAsie Occidentale in 1948. Schaeffer analysed and compared the destruction layers of more than 40 archaeological sites in the Near and Middle East, from Troy to Tepe Hissar on the Caspian Sea and from the Levant to Mesopotamia. He was the first scholar to detect that all had been totally destroyed several times in the Early, Middle and Late Bronze Age, apparently simultaneously.
Since the damage was far too excessive and did not show signs of military or human involvement, he argued that repeated earthquakes might have been responsible for these events. At the time he published, Schaeffer was not taken seriously by the world of archaeology. Since then, however, natural scientists have found widespread and unambiguous evidence for abrupt climate change, sudden sea level changes, catastrophic inundations, widespread seismic activity and evidence for massive volcanic activity at several periods since the last Ice Age, but particularly at around 2200BC, give or take 200 years.
Areas such as the Sahara, or around the Dead Sea, were once farmed but became deserts. Tree rings show disastrous growth conditions at c 2350BC, while sediment cores from lakes and rivers in Europe and Africa show a catastrophic drop in water levels at this time. In Mesopotamia, vast areas of land appear to have been devastated, inundated, or totally burned...