The music used in the Frozen Synapse Trailer

It is an arrangement of the title theme to the Super NES conversion of the original Civilisation.

If this link doesn't work I'm sure you can find it

Shotgunners have the quickest fire rate of a unit, which is key to using them to your advantage. If they're within range of another unit, say a Machine Gunner, they will get their shot off first and win the battle (but you also need to take into account the other factors that determine the winner: cover, are you moving, are you switching stance, and are you aiming).

As much as I hate camping, they're nice to camp a doorway and cut down anything that walks through it, or walks by a window they're camping.

And like it was mentioned above, they are the quickest unit, so if you're having trouble with a sniper, they should be your go-to unit, if you have any.