Elchim3900 Light Ionic Professional Dryer, Lightweight with 2 Concentrators Included, Black

Q: Does it have a cold setting? If so, do you have to 'hold' down the cold button, or just choose cold?

There is a button you click that determines the temperature. Once you select the position/temperature you desire, you do not have to 'hold' the button down. It remains in the position you select.

Q: (1)Is the warranty valid if bought through amazon?

I'm not sure - I haven' looked at the warranty. But I tell you this is by far the best hair dryer I ever bought. My hair looks professionally done every time.

Q: What is the EMF level (radiation that it generates)?

To my knowledge it was not specified in the literature. I do not have a gauss meter to measure it. Sorry.

Q: Anyone else got 2 different sizes of nozzle with them Elchim 3900 that don't fit?

Yes- mine came with 2 nozzles. At first it might seem they don't fit but you have to press hard to click in place. Once it's on - it's not moving! If you want to get it off - you may think it's stuck and won't come off but if you pull it straight out hard - and gently wedge something along the circular edge like a blunt knife you can work it off. What I don't like is the nozzle gets super hot and it's really difficult to rotate the nozzle as you are drying to get it perfect with the angle of how you are holding the brush. So you have to stop and let it cool or use a towel to turn it. I may return mine for this reason.