Ashley is definitely a mix of the real Calvin's worst girlfriends, or at least their worst qualities. And yes, she was using him as much as he was using her, but her ego, like Calvin's, wouldn't let her believe that he'd ever double cross her.
As for James and his orientation, you'll just have to keep reading....
No, the neighbor is not a famous bass player, but that is where I got the name. I wanted to use the last name, but considered Christine instead to honor one of the most beautiful voices we lost; however, I will like save that for another time or story.