A few class ideas
Here are a few class suggestions 
The spy-guy
Fast, with low hp and armor
Equipment: Silenced Pistol w/ scope, grapple hook?,camera?, explosives
The soldier dude
The standard frontline soldier, pretty high hp and armor
Equipment: Assault rifle, pistol, grenades, binoculars*, barbed wire?
* I had an idea of letting the soldier being able to mark what he is looking at with his binos, which then will be viewable for team mates. Something like: The solider looks at a building in the distance, which is full of enemies. He marks it, and all team mates know that there are enemies there. This would be good for aircrafts, which then easily would bomb that house.
The anti-vehicle man
The heavy guy against vehicles, some fat dude with much hp.
equipment: some kind of rocket launcher, pistol, mines, grenades, maybe a weapon against aircrafts...
The Engineer
The nerd, who is skilled with technical stuff. Medium Armor/ HP
Equipment :Shotgun, pistol, camera?
Abilities: Being able to somehow manipulate enemy cameras, repair vehicles, build turrets? (not the auto-shooting ones like in Team Fortress), build vehicles?
Some other classes that the game might need: Medic, sniper and a headless chicken.
Thats it for now
Fat people are hard to kidnap
-God (or was it Bush?)