The coal being old won't hurt anything, as you said it is all old!
You didn't mention if it had a barometric damper (is a round piece that fits into a T in the pipe and has a door that can swing in on it). If it doesn't have one you need to install one, if it doe have one you just need to vacuum the fly ash out of the horizontal runs of stove pipe. Also from inside the stove vacuum the pipe where it leaves the stove and make sure the elbow is not filled with fly ash.
You may still have to supplement the heating with your natural gas unit, since it is a furnace there is very little extra cost related to starting and stopping it. I would recommend setting the Tstats at whatever temp you would like it to come on and then run the coal stove. As long as the coal stove can keep up your gas furnace will never run.
I would expect you will use 3 to 5 tons of coal if you run the coal stove continuously. All the power cords you see are pretty simple once you understand where they go. There should be a plate that is attached to the stove with a electrical junction box and a small fan on it. There should be one power cord that comes out to plug the stove into the wall. There also may be a power cord that goes to a metal box on the side of the stove. This is a fume switch to prevent overfiring the stove. There should be two power cords coming out of the junction box that can connect to items on the stove, one goes to the distribution fan (up by the coal hopper) and one goes to the stoker/combustion blower assembly under the hopper. These cords may have rheostat cords hooked into them so that each can be adjust separately, or there may be one rheostat knob on the junction box (older Alaska stoves had both configurations). If you hook everything up the way I described you should be ready to light the stove.
I would recommend picking one of the methods in the light your stove thread and then just plan on a couple hours to figure it out by trial and error.
One more thing, if you do not have at least 3 CO detectors in the house that are newer than 5 years old I would go and purchase them and install one near the stove and one at either end of the sleeping areas. I also highly recommend that you have the one near the stove be of the type that gives a digital read out for CO level. If you have existing detectors you should replace the batteries now (I do this at the beginning of each burn season).
Please do not light the stove till you have installed/verified CO detectors.
I hope all this rambling has helped a little.