I checked out that site, and it seems they've fairly uneven coverage.
Also, it's not exactly the second coming of Quora.com.
If you want to build a website like that, I gather that the programming or front-end part is the easy part of the problem.
Your biggest challenge is populating such a site.
I would suggest that you hold contests or you reach out to bloggers.
In exchange for their answers, they get a link back or some sort of traffic rotation through your banner system.
Whatever the case may be, focus on populating your website if you're in any way, shape, or form serious about making it a success.
It's easy to put up a site; it's hard to fill it up with content.
Here's the bad news: people will go to your site for the content, not for its behind-the-scenes technical wizardry.
That's all well and good, but people are looking for actual value so focus on generating that content as cheaply as possible.
You can get it through contests or some sort of scraping in exchange for links.
Use your imagination because there are many ways to do this cheaply.
But even if you do outsource the content generation, it can be done on a bulk basis, and it doesn't have to cost you an arm and a leg.