I usually do this threads every year, and this will probably be the last, as this board likely won't even be here in a year.
From Art Adams:
Jimmy Hudson was originally going to look like Logan, the idea being that his genes would be so strong that his offspring would look identical to him regardless of who the mother was. This is why there's a Ultimate X height comparison with what looks like Logan-Wolverine on it.
From Nick Spencer:
That mysterious female character on the cover of Ultimate Fallout #5? Valerie Cooper.
The Ghosts were going to be revealed to be the product of Jean resetting reality at the end of the Apocalypse arc.
From Al Ewing:
Basically, the concept of of the new Ultimates book started with the name, and then Ewing made his pitch around it. Apparently Marvel still thinks they can get some mileage out of the "Ultimates."