First he needs to renew his medical.....then while you're doing that, verify and get him a new plastic certificate. You can request a number change, because all old pre-2002(ish) were issued as your Social ####. While all this is in progress, you can still fly with him, as obviously he doesn't have to have any of the above in posession until he's signed off and acting as PIC. I'd definately hit up those links above too.
BTW, didn't your CFI course touch on this stuff? I find it boggling that you didn't get some insight on this.