---> How to paste Print Screen on MS Paint automatically when press "PrtSc" button ?

I don't think you can do it faster...you have to tell it where to paste it...otherwise if it was automatic it might end up pasting it in programs you don't want, which would be even more annoying.

You can't but you can look for a program that does that.

You can't.
you have to open paint separately then do your printscreen, paste thang.

Just print screen and press control and v at the same time? Thats the only method.