Several posters mention to shut the engine off, then cycle the loader controls, then disconnect the hoses before you take the loader off the tractor. This relieves any pressure in the lines that will make it hard to connect. For the same reason, park the bucket with the bottom flat on the ground, or vertical to the ground. If you leave it cocked at an angle, it will continue to put a bit of pressure on the cylinders.
Nothing unique about those Kubota connectors. There are more expensive types of fittings used on larger equipment, but those fittings on yours are typical of nearly all small tractors.