The way I understand it (Although I could be wrong) is that you get a 1 year warranty on the screen unless you buy the 3 year warranty with it or buy a PC at the sametime that has a 3 year warranty which then covers the whole order for 3 years. (screen and PC)
No, I think the screen does come with a 3 year warranty by default. Though, if you buy it with a complete system the warranty is whatever you chose for that system. So if you bought it with a computer with a 1 year warranty then the screen only has a 1 year warranty.