Hex2/Hexs is a combination of all their names. 'H' and 'e' being for both Helios and Eli, and 'x2' is for Xanthias and Xan, with the '2' representing Shinjiro and Seung-Hyo, meaning it's supposed to appear as an 's' as well. 'Hex' can also be seen as a reference to Suzy, considering she's a witch.
....In other words, Helios is an attention whore. /votes for name change for band.
As of now, there's a grand total of sixty three characters. Ten will graduate, eighteen will become seniors, six will become juniors, and eleven will become sophomores. There are eighteen teachers/extras.
Several of Deborah's dialogue contains references to a lot of things:
Old Western Flicks/Television: Again, considering there's...alot she's watched. She's made references to Dallas and I Love Lucy, for example.
Trivia: Random bits everywhere.
Alf and Xanthias are similar in a few ways that possibly aren't very obvious, as Alf was meant to be reminiscent of Xanthias. Alf grows attached to people all too soon, just as Xanthe does, basically skipping being acquaintances or friends to being best friends. Alf having grown up and been on the city streets most of his life was also meant to be the opposite of Xanthias having grown up on the countryside, although previously it was implied that Alf did as well. The dislike Alf feels for cats is also meant to purposely contrast Xanthias' love for them, and even Isabelle was made for the intention of Alf having a female he was very close to, just as Eleanor was for Xanthe.