US have the M16A3, M4A1, Mk11/10, I forget which but I think it's an M110 either way and an M29 for support.
SMAW is the US anti tank, though there's no vehicles in the beta unfortunately.
Side arm is M9, but I've also unlocked the Glock 17C and the M9 tac, which is the same as the M9 + a flashlight.
You can change firemode and switch attachments on an off etc.
The Russians have the AK74M, AKS74u, RPK and Dragunov to start with, the Grach being their side arm and the RPG7 their anti tank.
I've also unlocked the PP2000 for all classes, it counts as a primary though, and the M870 shotgun.
Then obviously I also have the SV98. All the listed starting weapons are allocated per team, the US can't spawn with the Russian starting weapons, but unlocks can be used across the board.
It's seriously good.
I wish I could play it on PC though, having more players would be good, though the beta map might seem a little crowded, especially once you get into the metro tunnels.