BOB- The 50-93 works best burning NUT size coal. You do not need to watch the stove pipe thermometer, throw it away. This stove has a bi-metal damper, when set properly it will adjust itself, sometimes burning hot, sometimes not so hot. Yes, as you learn how to shake it properly, you should eliminate some of that waste.
STEVE - The "white, light weight crappy looking coal" you refer to is just ash, that is what you want to have left after your coal is burned. It is fully burned, pick up a piece in your hand and it will crumble to dust. Sounds like you did not shake it very well tho. That ash should be in the ash pan and pretty well crushed to dust after going through the shaker.
Sounds like your stove is burning too hot, is it too hot in your house? You should NEVER go through more than 50 lbs of coal in a 24 hour period. Check your stove for air tightness, gasket on the ash door, on the front door & around the glass. Make sure the hopper lid is fully closed and sealing well at all times. Is your damper door opening & closing or just staying open? Somewhere, you are getting way too much air.