1...err~m...Miley Cyrus, maybe?
2...
I've seen him some where...I think
3...I'm guessing Fergie?
4...pfft, Eminem. It's the eyes O_O
5...
...dunno this one at all...
6...my old maths teacher? :3
7...from the fact it's 'shopped, I'm going to say Bieber...