So I was walking around(destroying people in VL form) and I saw a Vampire running down the road, nothing real special about it. I tried to talk to her but it gave me the 'This person is buy' thing, so I decided to follow her and she ended up going into Duskglow Crevice. Unfortunately she died via bandits before I could get out of the loading screen. I didnt find much out of the norm in the cave besides a moth in a jar(which is awesome!). Anyone else have anything similar?

I followed someone once not a vampire but a noble. He got killed by necromancers when passing by fellgallow keep (I believe that is the name).

Yeah they added friendly vampires if you side with the vampires or become one..though they tend to be weak compared to you and Serana.

Closest thing to that I had was...I killed my first legendary dragon as I'm taking its soul a farmer runs up and says "I can't believe you killed that thing." then I talk to him and he turns into a werewolf and attacks me...

I havent had any werewolf encounters yet. But its gonna be fun to fight one as a VL

I found a random vampire woman running through the woods, I followed her totally ignoring the quest I was on and she stopped when she got stuck on some rocks down by a river. I took that time to kill a slaughter fish with an arrow and she went nuts screaming for me not to harm her. She turned invisible and hid behind a tree, eventually I lost track of her.

Random non-hostile vampires are now Schizophrenic.

Agreed.
Edit: Theyre also ninjas.