I'm not a haunt owner myself, so take what I say with a grain of salt...but I do know a thing or two about marketing, and how to create a buzz in the music industry. The big thing is to get your name out there. A website alone won't build a buzz. There's billions of websites out there...how will anyone know yours exists?
You don't have a haunt yet, which makes building buzz about your haunt rather tricky. You can try with press releases, but I doubt you have anything really newsworthy. You need something that makes you stand out from the rest. Right now, you're just someone who's haunting their backyard (or front yard or garage, whatever). That's nothing new. There's already a ton of people doing that. So you need to ask yourself...what sets you apart from the rest?
I'm not so sure your social networking site is going to work so well. Myspace and facebook are the giants in this business, and they're going to be hard to take away from. People want to join social networking sites because their friends are on there. Or it offers features no one else is offering. You probably won't defeat anyone on the features since you're using a free system, which I'm sure is rather limited. As for joining because their friends are on....it sounds like you don't really have any members. Another strike against you is it's a social networking site specifically for your haunt. I don't think there's a lot of teenagers out there who want to join a site to network with their friends and discuss your home haunt.
Now, if you ignore the social networking concept, it seems your key goal in this all is just to build a buzz about your haunt, which is what the website is for. You're on the right track, but again, it's hard to build a buzz when there's nothing newsworthy. What I think you should try is making a myspace page and maybe a group for your upcoming haunt. And then add everyone. Not just kids at your school. Not just your demographic. Everyone within your area. You can start with the teenagers though. Possibly ask some of the people around here who have a myspace to add you, to show support. But this is just the first step. You still need to have something buzz-worthy. Being a haunt is not enough. You may have a lot of friends on this haunt myspace, but the ultimate goal is to get them to the website. That's going to be tricky without some unique content. You know your town better than anyone here, so you need to figure out what these kids would want to see, and what they'd be interested in. Maybe have a forum to discuss things going on around town. Maybe you could organize haunt themed events around town.
I would abandon the social networking/wiki concept for your site. Personally I think it'd be confusing (is it a social networking site or a haunt site?), and I'm not so sure many teenagers really care about the wiki concept. It's very hard to populate any sort of social networking site. I've run a forum before, and I know it takes a long time to get a large member base...something my forum never acheived.
Looking at your website, it seems you're lacking content. And I can't really tell you your demographic is. Is it teenagers and potential customers? Is it people in the haunt industry? Is it general haunt enthusiasts? It's going to be difficult to be all three. Right now having your goals as the main content makes it look like it's more appealing to sponsors and investors than potential customers. As with any business endeavour, you have to ask yourself...what is your ultimate goal? You've laid out some goals for the website, but what is it all for? Is your plan to ultimately build more buzz for your haunt? To create a fan-site of sorts for haunt enthusists?