Zack doesn't have a recorded birthday date; Square-Enix did not release information on this.
Zack Fair was created in 1997.
Zack Fair was in love with Aeris/Aerith Gainsborough.
Cloud claims he was an ex-SOLDIER, when in actuality, he is basically impersonating a freind named Zack Fair who was killed. Cloud got the buster sword from Zack, Zack got it from Angeal. I recommend playing Crisis Core: Final Fantasy VII.
His full name is Zack Fair.
Cocaine
He doesn't have one.
Blue
He is 22 when he dies :(
Yes Zack did become hero he saved cloud and kept his honor and dreams.
Black.
Deep ones
It's called hairgel.