1) It was claimed by Westcott, in his History Lecture, that the Jewish people were taught by the Egyptians. It was common (and still is) to ascribe ancient wisdom to the Egyptians. Alchemy, for one, is a word that comes from "Al-Khem", or "from Egypt". Here is a little of what Westcott wrote:
It is therefore part of established Western tradition to hark back to older times and places, intimating that what is taught to initiates now is a continuation, in some form, of the ancient teachings and practices of the initiates of the past. This gives credence to those modern teachings and practices, and adds to the mystique of connecting to this "long-established" esoteric tradition."Through the Hebrew Kabbalah, we have indeed become possessed of more of the ancient wisdom than from any other source, for it must be born in mind that the Hebrews were taught at one time by the Egyptians, and at a later date by the Chaldean Sages of Babylon. It is A very curious fact that the Classical nations, the Greek and the Roman, have handed down to us but slight glimpses of the Ancient Magic, and this is the more notable because Greece succeeded to the Mastership of Egypt, and Rom to the Empire of both the Greeks and of the Jews. Greece indeed succeeded to a share of the Mysteries of the Egyptians, for the Eleusinian Mysteries were copies of those more ancient and solemn ceremonies of Isis, Osiris, and Serapis, but they lacked the true Magic of Egypt and further the classics retain but faint glimpses of even the Elusion Secrets. And these glimpses serve only to disclose the fact that the Eleusinian pupils were partly ignorant of the Isiac Mysteries, a notable example of which is seen in the use of the words, Knox Om Par, of which even they knew not the meaning, the words being merely the Greek incantation of the real ancient Egyptian words whose meaning has been a secret for centuries.
Hence the 0 = 0 grade of Neophyte is found to possess Egyptian characteristics and symbolism, and further an attentive study of the Higher Grades will reveal the source of much of the culture, and illustrate the language of the late Eliphaz Levi, through whose adeptship and advocacy the study of Occultism has been popularized."Westcott - History Lecture
2) Egyptology and archaeology was really kicking off at the time of the inception of the Order, particularly with the work of E.A. Wallis Budge. I believe the Rosetta Stone, for example, was discovered around a century or so before the Golden Dawn was established. Likewise, there was a lot of fervour and interest in the archaeological world regarding certain Egyptian finds. The Egyptian Book of the Dead is, in particular, a source work for Golden Dawn material. This "popularity" is believed to have influenced the Golden Dawn's emphasis on Egyptian forms in the Outer Order, and I agree that there is much truth to this assertion.