There are many fan groups that act out scenarios from various genres of films. Perhaps the best known are Trekkies.
Look for advertisements for such groups that you are interested in joining.
If you mean groups of real vampires then there are none in Seattle or anywhere else for that matter. Vampires are purely fictional.
yes vampire covens are found all over the world
There are many vampire covens online. They all claim to be real. Some examples would be the blood coven and vamp coven.
Twilight vampires have clans or covens.
yes vampires and vampire covens are every where.
The names of all the vampires and what covens their in.
nio vampier are not in the world only a bat Witches come in covens. Vampires come in clutches.
Yes. There are probably many. Covens are formed in many large towns and cities all over the world.
Yes. Their clans, by the way, are called "covens." you have to join a clan and work you way up gaining power as you go
Unfortunately not all covens are online and very few covens actively advertise for new members. A quick look at Wiccan Meetups, showed nothing for Belfast, however there is an Irish Pagan Federation who would be the best people to aid you:
There are no real covens of vampires, old or new, since there are no vampires- old or new. Sorry, also applies to unicorns, werewolves and elves.
Including the Cullens, there are seven different vampire covens. The Amazon Coven, the Denali Coven, the Egyptian Coven, the Irish Coven, the Olympic Coven (The Cullens), the Romanian Coven and the Volturi Coven. There is also the Volturi Guard, the American Nomads, and the European Nomads.
In a sense, YES the Volturi would be considered the strongest. For example, because they uphold the law and have the largest known vampire clan. But in other ways, NO they wouldn't be considered the strongest. Most vampires wouldn't ever join them because they have a very bad reputation, and some of those vampires (like Benjamin) have very desirable gifts.