You can drain it directly into a drain pipe. Just make sure the the top of the drain pipe is even with the top of the washing machine. If not, the water from the washing machine will drain all of the time. There is no valve in the machine to stop the water from draining. The washing machine drains using a pump motor.

No, it does not drain. The top so many feet act as a reservoir.

If you see no obvious drain plug, then just remove the lower radiator hose to drain the system.

Remove the bottom hose to drain the system. Remove the top one as well and flush from the top with a brisk flow from a hose pipe.

it depends on what kind of drain it is.