If it worked good with wood it will work better with soft coal they have similar but different burn characteristics.
"1. Will the flue run hotter with this coal then with ant?"
Yes and no
When the coal is in the first part of the burn it can be as hot if not hotter than wood. However when the hydrocarbons burn off it will be a lot like charcoal or anthracite.
"2. How much overfire air does it need compared to underfire for optimum burn?"
It will vary from coal to coal so I cannot tell you the exact proportions, but I would start out with the over fire open all the way and adjust it down from there. Once you get it set where you like it then leave it there when you add more coal.
"3. When added, should the stove be ran hot to get it burning good before turning the in air down, or let it smolder away?"
I would try to ramp it up a little. Just shake the ashes out of the fire and open the ash door up and let the fire "breath" till most of the coke is a nice yellow color then take a hoe and push the coke to the back. Then add the fresh coal onto the grate in a pile that is higher towards the fire door and gently slopes towards the pile of burning coke in the back. Note do not completely cover the burning coke because you are more likely to get a poof or more likely a lot of poofs.
"4. And any other suggestions you might have."
If at all possible you might want to see if there is any way to preheat the over fire air. What often happens with soft coal is the "tars" and "oils" in it will cook off and go up the chimney even if there is secondary air provided for it. The reason for this is the oil/tar vapors come off hot enough to auto-ignite right at the fire, but they cant burn because they have little or no O2 so it cant burn. Then comparatively cold room air mixes with it and by then its to cool to auto-ignite, however if the room air that enters is heated to say 200*F-300*F then it is more likely to burn.
Good luck and don't be afraid of soft coal. If it starts to act like it wants to go nuclear on you then shut down the underfire air and leave the over fire air open a crack. Shutting down the under fire air will slow down the oils from cooking off and leaving the over fire air cracked open will help keep the puff packs down.