You’ll still get the departure card on a one way flight. It’s attached to the arrival card and left in your passport when you get stamped in. You only have to fill it out when you’re leaving the country.
At the London embassy they also have a habit of stamping ‘employment prohibited’ on a non imm visa based on marriage to a Thai citizen! I know it’s not, you can work on those visas, but they’re an odd bunch in that office!
in the teakdoor thread the guy who got the visa said he has to do 90 day reports, plus a personal visit once a year. So I guess they’ll check his financials yearly, and also check he’s been doing his 90 day reports? I’m not sure what would happen if he ‘forgot’.