I enjoy smoke cooking in the barbecue style. This is not what I would class as a direct smoke as in grilling. My reasoning is that in barbecue, any fat and drippings fall into a pan and not the fire. The pan is also not over the fire, or if it is, it is full of water and so the drippings never burn. To control the temperature, usually the food is not over the fire in barbecue.
I understood the main carcinogen threat to be from burning grease dripping from the food. In barbecue, that shouldn't happen. It does happen in grilling.
As to the smoke's content, the wood burned in barbecue is almost always a hardwood, rather than a resinous pine softwood. Pine smoke produces inedible food because of the noxious smoke.
Lots of other questions in your post I can't answer.
Phil |