I'm happy to report that, after a long journey, my F512 has made it safely to its new home. I was able to unbox and open the case inside the warehouse where it had been kept for the last 2 days at about 50-60F. No cracks or checking to be found! (please insert sigh of relief here). I gave her a quick look over, it looks great cosmetically, like new condition as the seller had specified. Mind you, I will do a thorough inspection once the guitar has settled in. It's currently in my basement in its case where its a cool 65F and humidity of 40. I'll leave it be for now, although its really tempting to take it out and take her for a spin.
All in all, everything went really smoothly at the border. Once I crossed into the US, the warehouse was about a half mile from there. People at the Kinek Border Mail Depot in Champlain were super nice and helpful. So after checking the guitar to make sure it was ok, I drove back to the border, ready to be interrogated (am I the only one that's always stressed out when crossing the border, like I'm hiding a pound of coke in my car or something?). So basically, I declared the guitar, the border agent asked me how much I paid for it, I showed him the Ebay receipt for $2200 USD. The only question he had for me was: "Why is it so expensive?" to which I answered: "Well... it's a Guild F512 12 string guitar, the grand daddy of all 12 string guitars". He looked at me, silent, for about 5 seconds, and then said: "Ok. Go to cashier to pay xx$ in taxes. Have a good day."... and that was it. Not a single word about CITES regulations, import permits, rosewood, etc... He never even asked to see the guitar. It was like bringing in a case of toilet paper.
In any event, maybe I went a little overboard with the preparation, but rather be safe than sorry. Glad it all worked out.
I will post some pictures soon, after she gets here beauty rest and have had the opportunity to give her a good inspection.
Thanks to everyone for your encouragement and again to TX for the find!