The terrible FAQ:
Q. Who the fuck are they.
A. as defined by wikipedia, Gorillaz are an English musical and visual project created in 1998 by Damon Albarn and Jamie Hewlett. The project consists of Gorillaz music itself and an extensive fictional universe depicting a "virtual band" of cartoon characters. This band has four animated members: 2D (lead vocalist, keyboard, and melodica), Murdoc Niccals (bass guitar and drum machine), Noodle (guitar, keyboard, and occasional vocals) and Russel Hobbs (drums and percussion).
Q. are they alter egos of someone?
A. Actually, they are purely fictional, although Damon Albarn says 2D is based off a bit from him,
Q. How do they perform live? They be cartoon characters, yo
A. well gee nigga home b dawg dis be their magik:
They either use Musion Eyeliner (it does a peppers ghost effect) to project the band members on stage
Example:
or, the inexpensive option:
Have a whole live orchestra, and the singers on.
This works since 2D is basically Damon Albarns voice, and De La Soul and other guests just appear
example: