If you're looking for a historically accurate model for Egyptian magic, the problem is that there really is no such thing. Most of what is believed about the ancient Egyptian practice of magic in New Age mysticism actually originated in a cannon of writings purportedly by a Hermes Trismagestis that appeared between 100 and 300 CE in Greece. The 'Thrice Great' Hermes was reportedly a contemporary of Moses, but there is no evidence to suggest that any of the Hermetic Cannon originated anywhere near as far back as the storied falling out between the Children of Israel and the Pharoahs (which was covered extensively in a blockbuster bestselling book and made into a major motion picture starring Charleton Heston). The Hermetic Cannon claimed Egyptian origin, and indeed the Greeks themselves, noting similarities between their culture and that of the Egyptians, believed that the more venerable culture was the originator. Modern anthropologists point out that in fact the influence went both ways. This wasn't humility on the part of the Greeks. Prior to our modern zeal for innovation, every new tradition made a claim to antiquity, sometimes quite spurious.
So, the Hermetic tradition originated in Greece, with an Egyptian backstory that doesn't hold water. It had a smattering of Egyptian folk beliefs thrown in, but its influence was largely from the Greek philosophies of Platonism and Stoicism. In fact, there was more influence from Jewish and Persian sources than Egyptian ones. But, this is the important bit, the Hermetic tradition went on to influence every Western mystical tradition that followed it, including ones that claim not to be Western at all. It was the source of Masonry, Esotericism, Theosophism, Rosicrucianism and indeed the majority of New Age mysticism.
This pseudo-Egyptian Hermetic tradition is fascinating, and would make a great game, but the thing is that it already has. This image we have of the wizard with his robes and books and bottles of bubbling liquids reciting Latin incantations comes straight out of that Hermetic tradition. The reason why the incantations are in Latin is because most of the Hermetic writings were disseminated through the ages in Latin translations. In D&D, we are already playing this supposedly Egyptian system.
So as for what the actual Egyptian tradition was, we don't know enough about it to make a whole game of it. And the pseudo-Egyptian tradition is what you've been playing all along, though the figure of the Magus is no longer linked in our minds with the Egyptians, as it would have been even a hundred years ago. So, how do you get the Egyptian flavor back into the system?
You might want to try a kind of pulp approach. Go back and look at the pseudo-Egyptianism of the 19th century, or at least the fictional representations of it both in victorian adventure fiction and our modern re-imagining of it. Take the movie
Young Sherlock Holmes for example. Or
The Mummy. What will sell it is not historical accuracy, but details of the kind that the mystics of the 19th century used -- ankhs and fezzes and statues of long-necked cats. Hell, just do a Google image search for Egyptian artifacts and fill your world with the details you observe there.
This page has some interesting information and links for the use of Hieroglyphs. Egyptian literature was largely religious or instructional and written in verse, which was composed of sentences that were split into two halves of a single thought, balanced against eachother, e.g., "The generations come and go among mandkind/And God, who knows all natures, still lies hidden" or "More hidden than gems is chiselled expression/Yet found among slave girls grinding the grain."
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