Hi Peter, it would be better if the whole floor of the firebox was a moveable/shaker grate, but by no means an absolute necessity. I'd burn it the way it is and see how well it does.
With anthracite, It likes a hot fire as a base to start on. And all the air has to come up through the coal bed.. So get a good hot bed of wood coals, several inches deep, and add several inches of coal over the whole surface of the fire. close the loading door, and let the under fire draft feed the fire air from below... you will hear a lot of snapping, crackling, like 'rice crispies' breakfast cereal.. This is the pieces of coal cracking from the heat... Then you will start to have blue flames dancing above the fresh coal, and soon a red glow from below..
Once you have the coal fire established, then fill the firebox up to the top of the firebrick... Coal fires burn from the bottom up and the amount of heat is determined by the area of the fire, The duration of burn is determined by the depth of the fire, and how much air you feed it. So a small diameter fire that is really deep will put out a moderate/small amount of heat for a long time... A wide shallow bed of coal will make a lot of heat for a short period of time.
Any luck with finding Anthracite in bags?? Or local Bituminous?? You might try PM'ing some of the Wisconsin and Illinois coal burners to find coal suppliers... Or look at the coal suppliers thread at the top of the list of forums on the home page.