Yeah, but I'm afraid it could take his focus off of The last Airbender, which wouldn't be good.
She is probably not. According to this page, she is 15. But the page is not dated and her date of birth is not given. Though I guess the page is not older then 1 year, so that would make her 16.
When did Frank Marshall state that it would take 6 years, I thought they were going to do more of a Lord of the Rings type thing.