Hey Soloman, sorry for the late response. I had had little time as I was working n the "Pope QuiZ."
About the myth of the "White Horse": I am no expert on Egyptian theology but I do not remember the myth of the white horse.
It is my understanding that horses were not native to Egypt and has to be imported by the Pharoah's for use in war. See the book by Arthur Cotterell entitled "Chariot" My point is that Egypt was not a horse culture like the peoples of the steppes. Therefore, I wouldn't expect to see much of the stories of the horse in Egypt like you see in other cultures. But if you could find this information, all power to you!
PS: Consider the boat graves near the Giza pyramids and the boat graves near Abydos from the 1st dynasty, see National Geographic April 2005. RA also coursed the sky in a solar barque. Thus there seems much more about boats in Egyptian theology than horses!
© Charles N. Pope, US Library of Congress. All rights reserved.