Aren't most amateur hackers retirees in nursing homes with a lot of time on their hands? Nice to see an application aimed at a different audience (young women).
It's not necessary. But it does make a difference to the story. Some one who'd had years of education and gone through a good college and has worked in the industry could have made this, and everyone would have been impressed. The fact that this young person created this without all that is impressive.
And, depending what media you have access to, there's not often good news about young people.
Programmers seem to work for free on Linux and other projects, while designers seem to be more eager to get paid. Given these common memes, people may think that programmers are eager to do any kind of work for fun.
Here's a proposal: use your email address. Period. No password. Take your average bulletin board--you're probably not going to use your email address as your nym anyway. Even if you do, what do you lose if someone impersonates you?
limited-edition t-shirts
limited-edition action figures
dinner with the devs
cool gold-colored cd/dvd/usbkey/etc with the software
your likeness as a minor character
limited-edition plush toys
Basically any kind of promotional tchotchke you can think of. It would have little intrinsic worth but it would be RARE which means that if the product became well-loved it would be worth something down the line when you decided you no longer had room for it - and until then it's an item that tells people something about you. "Oh man is that the commemorative bong for Psychonauts 2? Holy cow I loved that game."