It looks awesome. if you could make a game out of Black Hawk Down, it would look like this.
So, specific answers.
Yes there is an extensive singleplayer campaign.
Its developed with the Frostbite2 engine and it was developed for the PC. The xbox version has been scrunched down. In fact one of the techs was telling me that when they first tried it on 360, it would barely render a single player object before optimisation.
Snipers are in it but i didnt get to see any play as them.
There is regenerating health like Halo.
Here's the shocker.... no dedicated LAN support. The lan has to have connection out to the interweb. He said would you be able to rent dedicated servers, "like before" ... which i hope makes sense to you.
I asked about commander mode and they all clammed up and wouldnt say anything. I doubt you will see it as one head guy did say "it was only 2 out of 128 people, its a lot of work for that"... but i expect some new tactical and strategic elements to MP because there was something they werent telling us.
They wouldnt say a lot about MP and certainly wouldnt answer questions about mods squads, mostly they wanted to show off the pretty pictures which were... in fairness... pretty.
There was one thing I loved, their destruction physics are amazing, you can tear down a 5 storey hotel to the ground, to rubble, or you can blow about a 1/6th of a breezeblock away from a wall to get a shot or to reveal an enemy in cover.
If we get another invite in the fall (as we sometimes do) I'll try to get a BF mod over to it, we've done it before for driving games mods. This was much more than BF though, i got to see and play Portal 2(awesome, gonna be huge!) and tons of other stuff.