What previously manual techniques should I use a stand mixer for?
I use mine for anything that needs to be kept fairly cool, but doesn't necessarily need to be "cut" the way the blade of a food processor does. Anything that requires mixing meat, in particular. Burgers, meatloaf, etc. retain a better texture when the meat isn't warmed by your hands. Aside from those, we mix ground meat for jerky and meatballs in the mixer.

Hope this helps. Enjoy your mixer!