Is the new vampire lord a seperate unique monster, or are they redoing vamprisim in general? So that just being a vampire gives you the skill tree and maybe you get the wings and abilities as perks.
Ie. Can you become a vampire, werewolf or vampire lord? Or can you just be vampire or werewolf with the new vampire lord replacing the old vampirisim.

I also wonder if one can be a vampire lord (creature) without having to side witth the vampres, or is it like the companions where you only become one by joining the faction.

Well, I heard that Dawnguard vampires are the volkihars, the group of vampires described in Immortal Blood, while the vampires in Skyrim currently are the cousin of the cyrodilic vampires. So yes it's a seperate type of vampire.

As I understand it the vampire lord is an ability on top of the old vampirism.

No

I think it's an improvement on the normal vampirism

http://www.gameinformer.com/games/the_elder_scrolls_v_skyrim_-_dawnguard/b/xbox360/archive/2012/06/05/the-elder-scrolls-v-skyrim-dawnguard-vampire-perk-tree.aspx

there you go

IGN has some more general info too.

Thnx for sharing