Just a few suggestions regarding the tracer rounds used in the game.

I think it would be nice if the tracer rounds were colored depending on which team fired them. Currently most NATO rounds have an orange/red red tracer, while Warsaw pact ones have green tracers. (At least, from what I understand) Just to give an example. Tracers can be many different colors depending on the chemicals used, in case you decide to just make up your own weapons and factions =p

Secondly I don't think that every round fired should have a clearly visible tracer. Typically every three or five rounds are a tracer, and if you still -really- want the tracer effect on non-tracers, you could easily have a very subdued white/grey 'tracer' streak. In addition, sometimes the last few rounds of a magazine are tracers, letting the soldier know they need to reload.

Third, tracer rounds should provide limited illumination at night.

If they are added, suppressed weapons will never have any tracers of any kind. That pretty much defeats their porpoise.

Lastly, ricochets, even if they cause no damage. Tracer rounds deflecting off of stuff looks cool, go look up a video of a minigun.

EDIT: Maybe only allow tracers rounds to ignite flammable liquids, aside from other explosions of course.