Like somebody else said, I think they would take a Vice City approach to eating, just go into the marker if your health is low and you will eat to give you more health. Or maybe they could do it like they did in Saints Row, where you could keep burgers and eat them at certain times when your energy was low. But maybe this time it would be somewhat different because they are taking a new approach to storing things.
About the sleeping, I would like to see what they did with Bully, not necissarily the same thing but just go to sleep and you can wake up 6 hours later not the next day. Maybe having multiple safehouses with beds so that you can go to various places to go to sleep instead of just one place.
Just a couple of things that I just thought about..