plot wise, I believe the idea is starting at either RE1/0 (they are still deciding how they would handle 0, as it only features 2 people) and you would "play" though the games in order. So we could play as Chris, Jill, Barry, Rebecca, Brad (Pilot's name right?) or Billy Cowen (Just retcon it that Billy went with Rebecca in case we have more people) and go through the house.
Granted, this is in pre-pre-planning phases, so I can suggest anything.
is there an SRD for d20 modern / d20 CoC? I'm fairly certain he would not want to buy anything before looking at whats free.