actually, US citizens are required to report foreign accounts with an aggregate balance of over $10,000 in a CY, especially when filing a return. It's not difficult. Just a yes or no answer. I've been reporting for years without any issues.
really? Do you know how difficult it is to smuggle weapons out of a country and into another? For some it may sound easy and it does happen, but not everyone in America has a gun. Stop generalizing about Americans.
You'll be fine. Don't plan so much. Just go with the flow and be careful with how you spend your money. It was easy for me to spend less every day. I just did a lot of walking to parks, wats, and malls. Mostly free too.
You should definitely find a way to teach English, even if it's a private tutor gig. English is a skill much needed in Thailand. My kids go to university there, and all their friends want to learn English. More nationalities use English as the common language in Thailand.
Why can't she come visit the US? Her visa is valid for 10 years. Sounds like she can visit as many times as you're willing to pay for the trips. Did you get a K1 visa for her?