May I offer an alternative to the sniper: Hugo Weaving.
Also:
Demo: Keith David
Heavy: Vinnie Jones
Soldier: Adam Baldwin (shame on you, Hzza)
Engy: Ron Perlman
Scout: Orlando Bloom (never a bad idea to have a babe magnet)
Medic: Robert Downey jr.
Spy: Vincent Cassel
Pyro: Uma Thurman is good. Alternatively: Milla Jovovich or you can always go with Angelina Jolie

As for directing: Come on, we are talking about the realization of a computer game, so it can only be Uwe Boll or Paul W.S. Anderson
