There's a site - www.shaftprofiles.com - that lists different numbers and you can select different models and graph their curves.

Butt stiffness is more or less the 'feel' stiffness. If you like your shafts feeling firmer, go for a firmer butt. Mid stiffness effects the bending feel at the top and the way the shaft feels when it loads (and unloads). Mid bend and kick point are intertwined. Kick point is a vague term to describe how far up or down the shaft the main bend point is.