HI Brad, you may have read about this already, but when a coal boiler is put in along side an existing boiler, all the thermostats, plumbing and most controls stay in use..
Read as much as you can about hooking up a boiler, then if you haven't seen an answer to a question post it here... But I believe most if not all questons are answered in the many boiler instalation threads..
One of the big problems is that every boiler instalation is different,, unlike a Ford Mustang site, where you just name the year and options, and someone can point you at exactly what to do, with houses and heating systems each is somewhat different.. so nobody can point at one fitting and say change this part to that part, hook it up this way etc etc..
So read as much as you can and take some photos of your setup,, go to as many manufacturer's sites as you can, for measurments etc..
As mentioned above,, if you have a retailer with Boilers coming in in December,, hustle on down there and give him a deposit,, otherwise you may be looking at February before you see a boiler..