Has there been any confirmation over whether less-than-lethal ammunition is in New Vegas? A lot of people elsewhere are hyping that, but I can't find official confirmation.

yeah, beanbag ammo is confirmed by a couple of the devs. How you find it/make it is another matter.

Beanbag rounds? lol when i want to shoot someone i do believe i would want to kill... But still i might still use them

The Cattle Prod is in and does KO damage, so can be used as a non lethal weapon. There are others but I forget what they are.

Boxing gloves are in too, I saw them in one of the videos.

What exactly do they do? It'd be great to make a pacifist with a cattle prod and a gun with LTL ammo, but will it knock the characters out for a certain amount of time, like with the needed characters (Sarah Lyons, Dad, etc) when they get damaged?

erm... kind-of like hitting a supermutant with a Gauss rifle - it knocks them to the floor. Whether it knocks them unconscious, and for how long, we'll have to wait and see

Yes.