Immigration officers won't ask for a departure ticket but airline stuff could. You can choose to argue or explain to them that you don't need one or, do like I do, just book a cheap refundable ticket.
the eVisa system shows all previous and active/current visas. I guess some of you who never needed a visa to enter Thailand don't know. I'm not from a visa exempt country so I know this.
Quite a bizarre and stupid question by the officer. For some of us there isn't even a Thai embassy in my country. I had to submit to the nearest neighbouring country.