[Gimp-user] keyboard shortcut for show mask? change opacity?

[Elle Stone <ellestone ninedegreesbelow com>]

"Layer/Mask/Show mask" let's you see the layer mask at 100% opacity. Is 
there a way to set up a keyboard shortcut to show the layer mask without 
having to traverse the menu? And can the layer mask be shown at less 
than 100% opacity, so the underlying image is partially visible?

Elle