Sure, it will fit. Other than the fact it will slacken your head tube angle by over 3 degrees, raise you bottom bracket significantly and wreck the handling, you're good to go It's usually not a good idea to put a 140mm fork on a bike that was designed around an 80mm fork.
When I see an adult on a bicycle, I do not despair for the future of the human race. ~H.G. Wells
It would not be adviseable as the geometry would be pretty wierd.... Plus the fact that putting a longer fork adds more leverage on your headtube and might ovalize it, or worse, snap the headtube off....