Yea I noticed that Chris's part looked ALOT more action oriented while Leon's looks more akin to RE2 (which is great). The mystery guys's story seems to be trying to reach a "middle ground between the two I suppose. I guess I am just going to have to dread playing Chris's side of the story. Its going to be such a slap in the face to go from horror to a freaken action movie in a Resident Evil game. Chris is fighting Mercenaries, has a entire team with him, and has a FREAKEN TANK! Definitely going to hate his side of the game if its all about action.
Why the hell couldn't Capcom just make a game for "action" with Chris as the star and Leon the star of the horror one? That would be alot better than forcing the "new fans" who love the new style of Resident evl games to play through Leon's part of the game (horror) and force classic fans of the survival horror Resident Evil games to suffer through Chris's action packed adventure.
And on another note.
I think the mystery guy is Steve Burnside. Look at his hand during the trailer. It looks exactly like Steve's when he mutates in RECV. And he looks to be around the same age Steve would be around that time and he even has the same hair color.
If it's multiple stories (a la Resident Evil 2), then just don't play the story you don't want to play. Besides, Chris is a member of a military. It kinda makes sense he'd have people with him. Besides, he said: "How many of my men died because of that 
BITCH?!?!?!" which probably means that his men are going to... well, die.
I think what the RE team is trying to do is 
not be like Dead Rising, and release multiple games just cuz someone wants to play as a certain character (DR2 for Chuck, and DR2:OtR for Frank). It's a waste to make two separate games for the characters when it's just as easy to put them in the same. Their stories intertwine in some way anyway.
Capcom's trying to cater to A) the fans of the classic games (RE1-3 and CV), and B) the fans of the action games (RE4 and 5). I honestly like both sides, so I ain't complainin'.
And on that, it was already confirmed there will be several characters, as well as co-op. Leon has his partner Helena, Chris has Beards, and Starkiller has "Ashley". Ada was confirmed to be playable later on. It was said there will be more characters.
As for Starkiller, I thought it was possible that it was Steve. That'd be nice, but I don't think it's likely.