Looks like you've given it some thought - but I'm going to play devils advocate here. (Note: I think this is a great idea, and would be cool if it worked out, just trying to look at it from a different angle)
In theory it looks like a great idea. From the top you'll see that you need a location, accommodations, vendors, a website, tickets. Most importantly you need
people
And the way you guys talk about the big deal of getting a domain name and "buying a website" makes you guys sound like technology noobs. Woooo 10 minutes on Go Daddy and it is done. Websites are easy and cheap. Hotel conference spaces are not always cheap but not a problem to arrange. Online ticket sales are easy too. Done it before many times. There is planning to be done, but it isn't that big of a deal. I have owned lots of businesses more complicated than this one. How many successful businesses have you guys started?
"Buying a website" is easy. Getting your domain, simple. You need hosting, the website technology, support emails (which require staff to man the emails) and online tickets sales. You need to prove that you are legit and won't steal the peoples credit-card information.
There is a big difference between a "licensed" event and a non licensed event. Probably 2/3 of my visitors will be 12 year old kids. They don't care about whether Mojang endorses it or not, they just want to hang out with other kids who love MC and talk about it and to play a bit and maybe meet Graser or Sky or someone.
You're not just looking at the 12 year old kids who are going, how exactly do you expect them to get there? Remember, we aren't playing Rollercoaster Tycoon, people dont show up magically. Would you let your son walk off into some place filled with a couple hundred kids, all alone not knowing the security and legitimacy of the event they are going to? One bad apple ruins the bunch. I'm sure I wouldn't.
All in all, it seems like you have given it thought, its just that some more extensive planning should be needed. I would try to get some endorsement from Youtubers and popular server owners, vendors to setup things for kids to do, maybe be sponsored by a server? A name and staff. There is more then meets the eye.
Good luck, and if you require assistance I might be able to help out.