I also want to thank everyone for good, useful replies.
I’m certain now that having my old passport intact (albeit marked ‘cancelled’ by the US dept. of state) will not affect the validity of the embarkation paper stapled in on my most recent return.
I’m still uncertain about whether or not I have to get a new resident visa.
This is the big sucker they stick in your passport once you are officially here and employed - issued by the Ministry of Foreign Affairs - Bureau of Consular Affairs. This is an office seperate from the National Police Administration that issues the ARC and puts the re-entry visa sticker into a passport.
This is NOT the visa Citizen K notes that “is stamped “Used” as soon as you use it to enter the country or have your ARC issued.” That’s the entry visa, and yes, as CK noted, that’s stamped as used in my passport. (Mine was a 60-day visitor visa).
This consular affairs visa covers a full page with a flowery little ‘visa’ imprint on the top left corner and an octagonal window with a dragon’s head below that.
I guess I know now that I can leave and return holding both passports; I just wonder if I’ve gotta go to consular affairs for a new big sucker. I guess I’ve got to.
Thanks again, and, anyway - “They’re nihlists, Donny, nothing to be afraid of.”