Hello BnT. I'm a bit confused. You said that you got heat almost instantly, do you mean that without the blower running, you had heat coming out of the heat outlet? Or did you mean you got the fire going almost instantly??
I think the fan has a temperature sensor that turns it on and off, the temp sensor may be bad, or miswired.
As for the smoke out of the hopper, this sounds to me like not enough draft to pull the smoke and gasses out of the stove and up the chimney. Do you have a draft gauge?? [A Manometer]. If you have a marginal, short chimney you should have one to keep an eye on the draft.
I'm thinking that with the stoker turned way down, the ash isn't being pushed off the end of the grate, and is building up, causing the fire to burn back into the bottom of the hopper. With the fire turned way down, there may not be enough heat to create a strong draft. The combination of the two means you cannot turn the stoker down that far. Keep it burning harder/hotter.
The larger the pieces of coal, the larger the pieces of ash. The buck coal ash will look like big thick cornflakes. rice coal ash looks like granola or grape-nuts breakfast cereal.
Is the dealer you mentioned the one who sold you the stove?? If so, get him involved in tweaking the stove to burn and opperate right.
Let us know what your find. We all learn from each other's experiences