It's fairly straight forward. You can either pick up the pass when you get yours. Or do it at a later date. Yes, the child will need to have their picture taken, and a parent will need to sign their liability forms. (available on this page http://mthigh.com/rates/seasonpass.html
) either at the resort OR you can download them, have them notarized with the parent's signature, and bring them with you.
Please bring a birth certificate for the child and note there is a $10 processing fee.
Hope that helps and please get back to me if there is anything else you need. Best wishes.