"Can I simply make flight reservations to leave USA, without doing anything else, receive a 60 day visa upon arrival ... " Obviously you'll need to actually come to Thailand. They're not giving visa exempt for people who don't come here.
The visa is less of a question but rather Airline requirements.
I have used WU in the past (10 years ago).. The were cheaper than an ATM.. But I had problems with them and their security practices. I think they had problems with verifying something or another. Their customer service was horrible. If you're going to use WU you should have a plan B, or emergency cash... But that's true for any transfer service.