1, I assume Aesir is more powerful in general due to the eyes stuff, but Jubby was only awakened with one eye so who knows how powerful she really is.
2. I think they explain it in the first game, but both clans had them placed in people's memories, in particular, those two. I don't remember what made them so special exactly.
3. That's what is implied, yes.
4. To piss Balder off to kill Loki.
5. It was only really the dragon dude. And because shit was outta wack (and her not noticing that fully until it was too late) that the dragon disobeyed her commands and attacked them. He's kind of an ass in general compared to the other demons.
According to the lord MB was based on, she was betrayed, and because of that, she understands how shitty it feels. Therefore, she isn't cool with doing that to her pact master. Plus she's not as mindless as the dragon is.
6.Those two aren't really running the show completely. Both sides hate her, but IIRC, if she keeps killing both as a balance, she gets a "get outta jail free" card when she dies. Or maybe I understood that incorrectly.
7. Aesir was messing with the balance, so I assume with that power, he just made both sides on his side.