I would say just put a business card in your EDC kit with your normal contact info. If travelling, notify the local US consulate of your whereabouts and if you're really concerned about being found in an alley, write your US passport number on a wrist band or directly on your wrist. Putting it in your EDC kit won't help since whoever conked you will have taken it. No need for stuff like your SSN or credit card numbers.

Yes, passport offices can figure out your passport number given your name/address/DOB.