Re: Billing order.
I think its safe to say that the 14 actors who attended the Comic-Con are the principal/main cast.
So they are the ones who would will get a billing in the posters.
"This is our chance to make a difference" - Sue Storm - The Invisible Woman
"He's stronger than any of us but he's not stronger than all of us" - Reed Richards - Mr. Fantastic
"We could these powers to help people" - Johnny Storm - The Human Torch
"You can't fix this, nobody can" - Ben Grimm - The Thing