I'm not familier with your particular boiler, however, bituminous coal will have different burning characteristics than wood or anthracite coal. It can be used to heat a home efficiently and without any more mess than any other fuel, anthracite included provided you have a decent setup. The 'fusing and melting together' that the previous poster mentioned is a characteristic of coals with a high Free Swelling Index FSI (or "high coke button" ranked 1-8, 1=less prone to swelling and 8=cakes and swells together tightly and strongly); there are bituminous coals with high swelling index which make it a real pain to heat with them and bituminous coals (most of them) with low swelling index. Metallurgical coal is a very high swelling coal, which is the last thing you want to burn; it might be higher in btu's and lower in sulfur but it's not even close to worth it. sulfur content is not important for home heating, if you don't want to smell any sulfur outside ever, you shouldn't be burning bit coal; there's not any discernable difference between lower sulfur bit coal 2% and higher sulfur bit coal 5%.
When looking for good coal for home heating and hand firing concern yourself with these qualities:
Ash fusion temperature- the highest you can find
Ash content- the lowest you can find
Coke button or FSI the lower the better (less than 4 is ideal)
you won't find everything you want in a coal but try to get as close as you can to the above and you'll have decent bituminous coal.