Benjamin Hays. Erewan Museum closest station is Chang Erewan. For Ancient City go to the end of the line at Kheha and either get Songtaew 36 or get a cab to Ancient City. Ideally you need min four hours for Ancient City. You can do the two in the one day, but get an early start to get the best value. At Ancient City you can use the open bus to get around or you can hire a golf buggy (can't remember the price, but it'll be on the website).
Benjamin Hays. Go take a look, but buy your tickets through Klook and then you'll get the same price as Thai people. You might be pleasantly surprised.
I think what Darren says is essentially correct, although there may be openings in selective premises, although he'd need to be involved in hospitality. So, for example, if he's French there could be an opening in a French restaurant, especially one attached to a hotel, where impressions are very important. If he's looking for a job waiting tables in a Thai restaurant, I think he can forget it.