Character development is my forte and something I prefer to focus on. And question, are you actually wanting to produce music that they will be signing? Or just focus on their development as a band and the bonds between the characters? Because if you actually want to do songs that will be created, I do dabble a bit in poetry on occasion so we could possibly come up with something. I am also looking up the bands you mentioned.
I personally listen to a majority of imported music, but I like: E.S. Posthumus, Nightwish, Celldweller, Lady GaGa, No Doubt, 3OH!3, and some other stuff.
As for a character sheet, here's one that's modified from an established character I've used for years but will tweak for this game.
Name: Belamine Leigngod
Parents: Benjamin and Elaine Leigngod
Siblings: Raul Leigngod
Occupation: College Student/Art Model
Likes: Sweet foods, light pink, dancing, and music.
Dislikes: Spicy food, stupid people, preps/jocks.
Hobbies: Sketching and painting when not involved with something related to the band.
Country of Origin: Romania
Back Story: Originally born in Romania, she spent most of her young childhood there. Shortly before she turned 10 years old, her parents immigrated to the States via job promotion and has become a duel citizen since. Able to speak English fluently, she has a slight accent still but blends in perfectly with American society. Having issues with her older brother, Belamine can be quiet a rebel and go against the example her brother led. Having an affinity for music, Belamine partook in school and private orchestras throughout her childhood and is actively skilled with many instruments. Also is very intelligent and does well in school but is built rather daintily, so she's often underestimated due to her size.
Instruments: Cello, viola, harp, guitar, and flute.
Hair Color: Black
Eye Color: Ice Blue
Attire: Usually seen in blacks or blues, she wears jeans and T-shirts often but also has a girlie side, wearing dresses or skirts. She has a taste for vintage clothing, and occasionally can be seen wearing items that appear to be from the Victorian era.