I'm pretty much with Radical_Dreamer on this one...All of that Janus to Magus stuff can be blamed on Ted Woosley...nyuk nyuk...
Although, Radical_Dreamer, I thought that maou meant demon king not wizard king...I had never heard wizard before...
To the first part: That's entirely possibly, given what he did to FF6. Meh.
"Ma" is a Japanese root word for things like magic, sorcery, etc. ("Mahou," for example, is "magical." However, then you get words like "Youma," which is another word for demon/monster/etc.) I've also seen "Ma" in things related to demons, like youma. Japanese is kind of hard to translate when it comes to concepts like magic, evil, etc., just because their perception of it is different from ours. "Ou" is king. So, both translations are, in fact, acceptable.