More thought, since you said you know nothing about a wood heater.
You need a hood or rain deflector on the top of the stack (outside) to keep rain out of your stack. Rain will cause your pipe to rust out quicker. You also make the pipe run just slightly downhill when it goes out of your shop. In case rain does get in it (some will), it will not run back into the heater and rust your heater out.
Clean it out in the spring after winter use. Ashes collect moisture and moisture causes rust. That thin barrel won't take much rust before eating through.
You'll need a "damper" in the smoke stack pipe a foot or so above the heater. It looks like a "T" with a flapper door. As the heater burns you will notice it leans in, fluctuates. That is from the outside draft sucking more air than your draft control in your heater door is allowing to pass through your heater. Also, if the wind blows a strong gust, without that it can blow back through your heater and blow a puff of smoke back into the room.
You can buy a draft control to go in your smokestack but with this heater kit your draft control is built into the door. The small holes in the bottom with the slide door to open and close the holes. You control how fast your logs burn by how much air you let into your heater. When you first light it, open them up, give it air, let it burn. But after you get it going good and the room warm, close it some, less air = less fire. On a hot bed of coals you could load the heater up with green logs and close off the draft and it might take 7-8 hrs or longer to burn the logs. Open it up, the logs don't last as long but it puts out more heat.
With a double barrel, the top barrel work somewhat as a heat exchanger. It basically keeps more hot air smoke inside, creating more heat. With a single barrel, you can build a flat top on it (or buy the kit) so you could cook or make coffee on top of your heater. I've cooked dinner many days on top of my shop heater. The wife is gone somewhere, I can prepare the pot inside, all ingredients-seasoning and let it boil on my heater. I don't have to run the stove inside while I am outside. After its done, bring it inside to finish, pick out bones, etc.
Many a meal has been cooked on a shop heater with your buddies drinking a few and waiting to devour whats in the pot.