Going to go with propane, thats the reason for the concrete base and concrete blocks.Looking good so far, very good workmanship! What is your heat source?
Going to slope it to the back, as far as the overhang goes I was thinking more for appearance on wether or not to do an overhang, it's sitting about 10ft from the shop where its dry, warm and I'll beOn the over hang the bigger the better .It just snowed here last night .Don't know were you are but just saying .What kind of roof are you thinking sloped to the back or hip etc?
if thats your small smokehouse..... show me a pic of the big one you could hang half a cow in there