I'm not sure if this will be included for future releases for the PC but hey, it's worth looking forward to.
As far as I know, this is for the console versions(PS3, XBOX 360). DLC for those Western version RE5s and separate disc for Asian version RE5s. Apart from the added scenarios, we get another set of costumes and at last, Josh playable at mercs. XD
Edit...
This is one if Chris' new costume. It's called Heavy Metal/Exoskeleton. Kinda cool. He's got a Gatling and a stun rod.
And this one, well... you already have it on the PC but this time, for the Mercenaries.
... that or Office Lady Costume.