Well, it had a bunch of knobs on the sides of the back and a dial and indicator underneath in addition to moving back and forth.
Water cooling is what your car/truck has. The system includes aRadiator, water pump, coolant (anti-freeze), etc. Air cooled is like your push lawn mover, where the only thing really cooling the engine is the air (maybe with the help of a fan) moving across the engine. The fins you see on most small engines help to dissipate the heat.
Personally, I would rather have the liquid-cooled version. As far as maintenance is concerned, if you can take a jug of coolant and pour it into the reservoir under the hood, you are in good shape. Keep in mind, especially when mowing, both the air-cooled and liquid-cooled versions need to be kept clean. Grass, dust and chaff build up can cause both systems to overheat. As far as the turbo is concerned, there is (as far as I know) no additional mx required. My experience in other turbo-charged engines is to let the engine idle for a minute or so before shutting it down, giving the turbo time to cool off.
You may laugh, but one of these saved my life when I took a mowing job at a local airport and had to use their machine with no cab!
Tractor Umbrella - 54 In. By Femco - Mills Fleet Farm
And they are cheap and light!