Welp, I don't know anything about $100k and I have all my former state side address coming here, to include SS and have not had a problem. That may change tomorrow, however. A former neighbor who had been here 23 years said he used his stateside address for his SS with no problem. All I know is I file my taxes via Turbo Tax and also the FBAR to cover my 800k sitting in a Thai bank wasting away.
I'm in Udon Thani, been here for 13 years, three times I got the letters late for all three times they send them out except one time only got the middle letter and it was a month beyond the reply date. Had to send the form to Manila for them to input. I guess just the luck of the draw. It's the only mail I get except for updated credit cards.
Keep a US address for your social security. If not, you have to fill out a I'm still alive form yearly and hope that the postal system finds you here in Thailand.
We have the overpriced Fortuner. It's OK if you can keep the rats out of the engine compartment. My daughter has the Izuzu Mu-X which is cheaper and looks and rides great.
I brought my Weiner dog from Korea in 2011. Paid to have the import papers prepared at a kennel in Seoul, and put a picture of the dog on the crate with her name so the handlers may see her as a living thing rather than just cargo. We flew Asiana and I forget where we picked her up at the airport when we arrived but it wasn't a problem. My Thai wife did all the talking with the customs folks, paid around a thousand baht and that was that. More stress on us than the dog. I really think having her picture and a Hi, my name is Coco on the crate helped with her handling. She got a lot of attention. Hope this helps.