You briefly mentioned Reddit, it sounds like there's a lot of potential overlap in the demographic (and certain subreddits, especially AskReddit). You might want to add a "How is it different from Reddit".

Also, I'm still struggling to understand the vision from your description here and there. I hope you can find a way to be more succinct. The main example I see here is Kate Middleton's dress, which afaict would be fine on Quora.

Also, I don't know why you say Quora doesn't like humor, it allows and (and heavily upvotes) questions like http://www.quora.com/Brogramming/How-does-a-programmer-becom... whimsical questions like http://www.quora.com/Superheroes/Given-our-current-technolog... which would never be given the time of day on Wikipedia and probably not on a relevant StackExchange either.