Surface Pro 3 Hotkeys

Screen brightness:
Fn+Backspace = dimmer.
Fn+Backspace = brighter.

source: http://www.lovemysurface.net/surface-pro-3-screen-brightness/

Closing a window:
Fn+Alt+F4

source: https://pricklytech.wordpress.com/2014/08/05/surface-pro-3-quick-tip-alt-f4-does-not-work/