I believe AnneRice, author of Interview with a Vampire hosts an event at her home. I always wanted to check itout.

There is the Museum of the Dead if you like creepy stuff.

LOVE New Orleans! Great city! I'm jealous, been there 5 times and always willing to go back!

I'm from New Orleans. Lived in and around the city almost all my life.
I don't know anything about the "vampire culture" here. There use to be a lot of people dressing up with the fake teeth a number of years ago, so maybe that's what you are talking about. But it's possible I just don't run in those circles.
I'm trying to think of anything special that is happening that's not just a show for tourist. I've talk to people that have gone to voudou rituals, but I have never. There are tones of parties of course. I might be too boring to offer any advice.

There should be a ton of things going on, and you'll have a great time.. but be careful...
There is a lot of bad stuff that goes down there too

I've never been, but there is an annual Witches' Ball I'd love to attend some day, but I think it's kinda pricey. Just google and I bet you'll find it. NOLA is my fave city in the U.S. Can't go wrong there in my opinion.