Short answers, pulled from the story.
Smoking food likely dates back to the Paleolithic era, making it one of the oldest food preparation practices known. It was later combined with salt-curing to create a highly effective preservation method adopted by cultures around the world.
The Torry Kiln was invented in 1939 at the Torry Research Station in Scotland. It enabled uniform mass-smoking and is considered the prototype for all modern large-scale commercial smokers.
Hot smoking is typically carried out between 52 and 80 degrees Celsius. At temperatures above 185 degrees Fahrenheit, food can shrink excessively, buckle, or split, and yield drops as moisture and fat are lost.
Guaiacol is the phenolic compound most responsible for smoky taste, while syringol is the primary contributor to smoky aroma. Cellulose and hemicellulose in wood caramelize when burned, producing carbonyls that supply sweet, flowery, and fruity notes, while lignin generates spicy and vanilla-like compounds including vanillin and isoeugenol.
Cold smoking temperatures, typically between 20 and 30 degrees Celsius, do not cook the food, so pathogens are not killed during the process. The US National Center for Home Food Preservation states that most food scientists cannot recommend cold-smoking methods because of the inherent risks, and advises that it be handled only by personnel certified in HACCP.
In Iceland, dried sheep dung is used to cold-smoke fish, lamb, mutton, and whale. In New Zealand, sawdust from the native manuka tree is commonly used for hot-smoking fish. Some North American ham and bacon producers smoke their products over burning corncobs, and peat is burned to smoke the barley malt used in Scotch whisky.