Lets deal with the overflow problem.
If the water does not stop when you shut off the machine your water valves are stuck and will need to be replaced. An easy and inexpensive repair that you can do.
If the water does stop when you stop the machine, the problem is in the water level control system. The way it works is that there is a plastic tube from the water level switch down the side of the tub and when the water fills the tub it fills this tube. This increases the air pressure in the tube, and when the water is at the correct level it causes the water level pressure switch to click and tell the timer to stop the water.
You should first try cleaning out the plastic tube, take it off the water pressure level switch and blow it out. If this does not fix things replace the water level switch itself.
So, you should get your washer working ok, and then you can see if the noise in the spin is so great that you need a new machine.