There are a lot of groups which fit under Kemeticism, and what groups it covers are generally different based on who is determining what Kemeticism means. For me, there are Kemetic reconstructionalists, Kemetic revivalists, Afro-Centric groups, and Tamaren groups. I make these four groupings based on the people I've seen who work with Egyptian deities and/or cultures.
Kemetic reconstructionalists tend to put an effort on making things as exactly the same as possible as back then. These people tend to do a ton of research and then try to copy what the ancients did exactly as they did. This group tends to be in a minority when compared to the others, because it's nearly impossible to accurately do this. The Egyptian religion lasted a very, very long time, and they (like Christianity) changed, grew, and diverged from their original beliefs. Each city had their own principle deity, and the nation wasn't always united as a nation.
Kemetic revivalists are (essentially) Kemetic reconstructionalists who don't try to copy things exactly as they were, but try to follow the concepts and do things as they are and as the netjeru (gods) ask of us. Revivalists sometimes do a ton of research and other times they get orders and then research into why they are being asked to do something. Not all revivalists are heavily researched, some are and some aren't; it depends on the person. This is where revivalists tend to have issues.
Afro-Centric groups are rampant in any discussion on Kemeticism. These groups are composed of people of African descent only and tend to have purely or mostly political aims. Very rarely will you find one of these groups involved in spirituality, and when they are they will often make comments regarding the spirituality of Kemetic organizations that accept people of different color. (I'm not of African descent however, so I can't state explicitly what these groups are like. This is the impression I have gotten from them based upon their group forums, their own websites, and the Youtube videos some have made. In regards to the color comment, yes, sometimes how dark one's skin is effects whether one can join these groups. I've known of some people of the right background being turned away because they weren't as dark as the group dictated.)
Tamaren groups are the most common. These are groups (or people) who are not necessarily reconstructionalists, revivalists, or Afro-Centric. They may work with the netjeru or a netjer (deity) but they don't necessarily work with them in a Kemetic or Kemetic inspired way. This includes Wiccans and eclectic individuals who work with the Egyptian panthneon in a decidedly Wiccan/eclectic way.
In regards to specific comments:
Ra is one of the principle deities, but not necessarily the principle deity. He is also more than just the sun. The sun itself is the Aten (the physical representation of what Ra and others are).
Not all groups under the title Kemeticism are Neo-pagan groups. The Kemetic Orthodoxy is an African Traditional Religion, like Voodoo and various others are.
Habdonia is a Hellenic goddess, while Hathor is an English translation of a Hellenic name of an Egyptian goddess. Hetheru/Hwthr are the most common translations of their Egyptian names into English.
Tour Egypt is one of the best resources online, along with Henadology. Henadology is pretty awesome for lesser known deities.