I've been doing a little research on Devadatta. In traditional art, he's the one figure in Buddhist lore who is traditionally portrayed as being swallowed by the earth and pulled down to hell. When that is compared with the imagery in MW, it yields some very striking parallels, and some striking differenes. After all, it isn't Yuki who fears hell in MW.
As for the biography, Tezuka invented a fair amount of the motivations and backstories. For example, Ananda was Siddhartha's cousin, who grew up wtih him and was devoted to him. Bimbisara (played by Rock - which continues to get my brain going in circles) was an actual historical figure of the times, and what happened to him is pretty much as portrayed, minus the prophecy, which is a pretty key piece.