With the water pump, there a specific thread about it here. It's basically the solenoid in the supercharger clutch assembly which causes the squeal. There is back and forth "discussion" about whether it's a problem or not. Replacing the pump may or may not fix it, or if it fixes it, it may reappear. Volkswagen have tried several designs and thus far all eventually squeal. The squeal was apparently undetectable with the MKV GT even though they shared the same engine, so no one on the forums is really sure why you can here it in the MK6 but not the MKV - though the MK6 GTI has a rattle "characterist" in the exhaust which some people notice but wasn't present in the MKV with the same parts...