We are definitely using Traits from the Advanced Players Guide. I’m also considering using Hero Points from that book.
I would consider borrowing the character background creation rules from Fate, but it doesn’t seem necessary given how the Traits work to tie the characters into the adventure. (See Party Dynamics for more on this).
Hit points will be determined using a variation of the White Box rules. First level characters will have max hit points. From then on hit points will be re-rolled each level. If the new total is greater than the old total, then it will become the current total. If the new total is less than the the old total, then it will be ignored.