From what Ive been gathering from news and forums is this.
-New Shouts-Lets you command the undead
-Two New Houses-One being a fort you can deck out
-Bone Weapons
-Crossbows
-Craftable crossbow bolts
-Two new skill trees
-Werewolf skill tree
-Vampire Lord Skill Tree
-Vampire Lord
-(Dawnguard Only) Ability to hire armored trolls (WTF)
-New Dragons
-New Horse

Rumors (Gossip I heard from friend and the community)
-Snow Elf as a playble race
-Child Adoption

If theres something you know, that I didnt put on the list tell me

The snow elves or falmer are forever mutated, they aren't coming back thats just something the fans want but is never going to happen.

there was leaked info in the last patch which contained snow prince animations. also todd has avoided answering whether they'll be in, and says we'll have to wait and see. sounds just like what they said about werewolves tbh

Snow prince is dead, and those weren't animations they were more of furniture.

They were animations and you forget three things:

-The DLC is about immortal Vampires.
-In the DLC you'll visit the Soul Cairn, a realm of the undead.
-Elder Scrolls will be featured in the DLC and as we already know they are able to do many things like traveling through time.

So there are enough ways for this DLC to bring back a dead character.

The problem with the vampire thing is that the snow elves died out before Molag Bal created the first vampire and the Morrowind DLC Bloodmoon had the Snow Prince in it, as a dead body. Also the whole point of the falmer and the appear is that they are a mysterious race like the Dwemer, another race that will never be fully explained or brought back.

As for the Soul Cairn you may have a point but most likely the Snow Prince would be a ghost or something, not a full blooded, unmutated Falmer

Should we see the prince this is how