I find the "First name only" thing on ESTA a bit off. Like many ethnic Chinese, I have a Chinese "first name" and an English "Christian" "first name". In the end, I entered both into ESTA as one long first name and it was valid and the application immediately approved. At immigration, I'll just explain it to the CBP man if asked. I wonder what happens if the person only has one name i.e. no first name/last name, just one name.

For tourism and business, I was never asked for proof of occupation though CBP did ask me for my occupation. In fact, I don't remember ever giving any additional documentation ever except in the pre-9/11 era when arriving in US to attend grad school (and that was just only for the initial arrival).