A properly burning stove, not an insert should burn about 3-5 tons of Bitum for a season. You may not do as well with your furnace, some heat is wasted when the fans are not running, I'm not sure if you have a constant running fan or thermostaticly controled.
So you should be fine for this season. You will have soot issues with that high-volitiles coal... Soot, from the unburnt volitiles will attach itself to the inside of the upper firebox, heat exchanger, and inside the flue and chimney. You may find your draft diminish over a few weeks, and you will have to clean the chimney often.
Coke, is bituminous coal after it is cooked by the fire, but the coal hasn't burnt up yet. The volitiles are all burnt off, what remains is almost pure carbon.
Read up on the burning bituminous threads. Each mine or regional area's bitum coal has different characteristics.. Some have high volitiles, and make huge volumes of smoke, some has high swelling index and will get soft, sticky and swell up when heated, each piece sticking to the next, making a hard bridge or crust over the fire below. Some bitum has very high ash content, seems to fill the ash pan in 6-8 hours, etc... Some bitum is really nice, very near anthracite to burn, some is really nasty,
Let us know how your luck is going with the coal.. remember a deep coal fire is happy, a shallow fire will go out easliy. make the coal bed deep, shovel it in till it is up to the top of the firebricks, and control your heat output with the combustion blower fan and under-fire draft controls.