you are correct. the only possible way to take a dog from Thailand to Ausjailia is via living 6 months in a verified country such as Singapore or Hong Kong. This ultimately saved me from my missus who wanted to live in Ausjailia as we have a Pomeranian
Best thing is to get the non o for 3 months in your home country and then open your bank account in the first month to get your 800k in there with 2 months + before your extension requirement. Pretty easy still
Anytime will be a good move from USA to Thailand. If you can do it now do it now. As a couple you pretty much need to figure out what you both wish to do with your retirement but wouldn't recommend Pattaya. My missus quite rightfully said Pattaya wasn't an option for us due to the temptation that faces men in that city.
I'm Aussie but 3kusa is a pretty decent budget here. It's around 100k baht a month. When I was single half of that was my living expenses and the other half I spent on girls. You could spend less on girls but I loved soi6 girls mostly so paying a few drinks, room cost and the girl came to around 2500 baht or there abouts. But you could still get fit freelancers for 1500 to save a bit more. So even though Thailand is more expensive these days, 100k a month is still a good life