Voodoo Extreme has a streaming feed of the trailer up, and they've also got some comments from Pete Hines:
1) Yes, that's in-engine (in-engine means it's done with game assets in
our rendering engine, but isn't done real-time. If it was done in
real-time, that'd be gameplay footage. This isn't something, for
example, that was sent to some house [e.g. Blue Studios] so they could
build assets and render it out, and create something for us to release
[e.g. Dawn of War 40K intro cinematic]).
2) Yes, that's The Ink Spots singing "I Don't Want to Set the World On Fire"
3) Yes, that's Ron Perlman [voiceover man extraordinaire of Fallout 1 and 2].
Damn right Ron Perlman.