I believe you get files when shooting the blue medals. (you can read them as a reward)
As for story understanding, play Chris' campaign before you play Ada's for the best experience. Other than that, it doesn't really matter. --- See you later alligator, after a while crocodile, don't forget to write.
The blue gas is still the C-Virus. Basically, C-virus in gas form = zombies, while C-virus injection = J'avos. Also, in addition to about the emblems, it's not like how it was back in RE5 where if you shoot an emblem in co-op both players get's it, so you're better of getting them yourself, plus there's a few emblems only certain characters can shoot. --- There is a Ghost in my attic and he says: "It's very dark up here...." ....Oh right....and he also says: "Boo."
I'm very undecided for next campaign, guess i'll go with Jack because Ustanak intrigues me...altho since i play on vet i know its gonna be frustating. --- Farewell MGO, the first love will never be forgotten. 06/12/12