Xbox user, so I haven't tried it.
Hope no mods are broken though, especially good ones. I modded Morrowind so I know that feel bro.
I think it'll be alright anyway, though, because the modder released the source code for it, so therefore, if any issues crop up as a result of Dawnguard, one could just go in and fix it, probably with permission from the modder if possible, but it can be done. The werewolf mod for Morrowind got updated after the release of Bloodmoon, though I never actually used that mod, since I haven't personally owned a copy of Morrowind THAT long (I think I got the Steam version of Morrowind maybe late last year or earlier this year).
From the evidence so far... I really cannot say.
Vampires are getting a full perk tree along with their storyline in the DLC...
but werewolves are also getting just as good a perk tree.
The question is where that perk tree comes from story-wise.
Yeah, this I find a little troubling as well. It's sounding like so far that the perk tree for werewolves will just simply appear as soon as you are a werewolf AND have the DLC installed, but that would be a rather odd way of doing that compared with the vampires, though. I have thought possibly that they may be doing a new minor faction for werewolves to join, and it is there you gain access to the perk tree. One of the confirmed perks suggest the possibility that they might be adding werewolves as encounter creatures to a certain degree, though it could easily just be that the summoned werewolves will just spawn from nowhere and fade away again after a certain amount of time. Encounter werewolves would be pretty awesome, though.