Weapon won’t be restricted by class, but rather by body type. It won’t have the ‘Engineer always uses a shotgun’ syndrome. If you can’t use a big gun, it’s because you’re not a big guy, which makes sense. About snipers, I will use excerpts from interviews:
[I]“We don’t have any really hardcore sniping in this game. There is a more accurate rifle that fires a bit slower, but the whole sniper alley thing just isn’t enough fun for enough players."
“There won’t be any snipers poppin’ headshots from 2 miles down the road…When you and I are killing each other, I can see the whites of your eyes.”[/I]
Class abilities, this is what I’ve read:
Engineer:
They construct and repair objects, can build turrets (perhaps more) can lay landmines, and can upgrade the power of teammate’s weapons.
Medic:
They can heal wounded teammates, revive downed teammates,
and increase their total health.
Soldiers:
can supply the team with ammo and plant explosives. (They may have access to more weapons than the other classes, like in previous games.)
Operative:
They can disguise as fallen enemy players, interrogate to get information, and can also hack into
security terminals and sabotage equipment.
You will also be able to ‘purchase’ and/or unlock upgrades for all the classes.