I will say this 180 rounds per minute is a little slow for a belt-fed 7.62 mm LMG. However, from the feel I get, I bet its rounds hit like a Mack truck and a 3 round burst does horrible things to the infected. 

Also... Would there be marine units deployed with plasma ejectors/flame throwers to destroy the spores?

What about incendiary grenades? Also most squads (10-15 men) usually have two grenadiers or guys equipped with grenade launchers. Any chance of them or their gear being in the unit. Everybody would be trained on them, but only the best with those weapons would be carrying them at the time. Also, any sidearms in the unit?

I do like the M96 rifle. It's actually a freaking huge round, bigger than a .50 cal. Basically it.s a .787 cal. 800 yards seems a little short, but I blame that on a scope that's less advanced than the current US military's ACOG site. But then again in an urban environment, I don't suppose you're going to need to reach out and touch targets farther away than that, unless you're on a specific fire mission for a specific target. For something like that you'd probably need a spotter, ballistics/targeting computer, and a good flight corridor. I know that the CheyTac M200 Intervention is currently delivering sub-MOA accuracy at 2300 meters, with reports of hits at two and a half miles. However, I think by what you've laid out this weapon is designed for precision delivery of maximum materiel damage, and the biggest temporary wound cavities you can afford in a sniper weapon platform. Loud, but will probably blow most targets in half if they're fairly big. May rip a small man to pieces. 

Overall, I think the M96 works, but think it is capable of a lot more with the right things, and the right situation. 

What about secondary gear, such as Kabars, water, rations, medical supplies, short range radios, smoke, survival items (like ferro rods), NVG's, NBC/M.O.P. or Environmental gear?

Also, instead of being pure marines in the group... perhaps we might have a few civilians to evacuate with us?