First Deck

First of all tell us wether it is an Extended, Modern or Standard deck. Most of its cards are Standard legal but cards like Vampire Nighthawk and Quag Sickness make it Extended.

Interesting mix of cards. I like the theme you're going with. I'm not terribly good at deck construction, but here are some of my thoughts:

The Vampire Nighthawks for example are rather quite amazing. Get rid of the 2 Markov Patrician and put in more Nighthawks. They both costs three mana, but the nighthawks will last longer and are more of a threat with their death touch. Gatekeeper of Malakir are useful too.

Malakir Bloodwitch and Anowon, the Blood Sage would bet better choices for your high mana cost spots. The Bloodline Keeper from the latest expansion would work nicely too.

Look into Urge to Feed instead of Dead Weight. It can still kill something small, and can make your creatures bigger. However, as Dismember would work better, but they're most expensive to buy.

Might want to add another couple of lands. See how it plays out though, might not be a problem, most of your cards have low mana costs.

You've only got 10 red cards, I'd almost consider taking them all out and sticking only to black cards. Into the Maw of Hell and Night Reveleres are rather expensive for what they do. Better to find another more useful vampire, and add another cheap kill card. A Go for the Throat or two perhaps.

As a fairly new player, I imagine you just play with your friends? Card legality isn't a big deal if you're just playing for fun. I've been playing on and off for nearly 10 years now, and most of my decks aren't legal in any tournament format. They don't always win, but they're still fun to play with.

In general FNM is usually going to be constructed standard, which means 60 card decks that validate to the standard rule sets.  Right now standard includes cards from Scars of Mirradan forward with a few cards in that time line that are banned OR they will run drafts, which tend to be block or the most recent expansion, which happens to be Innistrad.

You can probably find someone to play with you before or after the main events; however, extended at least in my experience has not been a very popular format.  Your extended deck may also qualify for modern; however, the site currently does not validate a deck against multiple formats.