You did good! The implements make that a -very- reasonable price.
Yes the only engine shutoff is zero throttle. These things are about as simple as a rock. No fuel solenoid, no fuel lift pump (from tank), no glow plugs (just a $15 manifold heater that's simpler to replace than a spark plug), no thermostat, only two cylinders, obviously no computer or exhaust injection system. Same alternator and regulator as early Datsun so these are inexpensive at Autozone. Owner's manual discusses running without battery if you have one battery you carry around and start several rigs with each morning, and it cautions against using dirty ditch water in the radiator. Really, a carpenter's hammer is about the only thing simpler than these early Yanmars. I think its partly because these engines were first developed for tiny Japanese offshore fishing boats where reliability is the only thing that matters.
Condition of your new YM2000 looks about the same as my YM240 when I bought it in 2003. I see washers welded for the front wheel lug nuts (and the paint burned off), somebody ran it too long with the lugs sloppy loose and squeaking and hogged out the holes. My YM240 squeaked as it rolled and I found all the lugs loose, prior owners just didn't care. The good news was a month of tinkering with minor 'deferred maintenance' like replacing the ThermoStart, the unreliable ignition switch, and the clutch safety switch somebody had butchered, got me back to spec and restored flawless reliability. Now I've enjoyed 13 years of troublefree service. I think this is a better record than many tractors bought new.
You're going to love it!