That Adora and He-Ro look awesome...not too sure about the color scheme of "classic" sorceress though. I like the new one alot.
And since we're talking about how we think MOTU fits together, my belief is that the Green Goddess is King Grayskull's mother, and that she took the form of a mortal woman and mated with the chief of the Jungle Tribe, gave birth to the future king, and then left her husband. KG grew up and then had all the adventures that we saw in the early mini-comics, but with Veena instead of Teela, etc.
He-Ro I'm not sure about, but I was leaning toward having him be not connected to the Power of Grayskull, but rather a mighty mage from another time who appeared in Pre-Eternia's time of need, gifted with powerful magics. He takes up the role of champion of Grayskull and is bestowed the crest of He-Man as a reward for saving the Castle from some grave threat. I was thinking being seperated from the "Power of Grayskull" would help diversify the characters, and I liked thinking of He-Ro as that Gandalf/Merlin/Pug type of character to He-Man's Arthur/Conan archtype.