*cough*
Err, no offense, but I can't imagine them eating humans or Aliens. Maybe some other species, but not the prey we know that is their favorite. But then again, humans and Aliens may not be there favorite, just the most important and the most challenging, making them the most fun to hunt.
Again, as for the smoking, they probably do it before hunts. We actually don't see this in Predator 2 or Alien Vs. Predator, but it's a possibility that they smoke only a small douse of it as a belief for good luck on a hunt, or something like that. I don't know, I mainly know my stuff on Aliens better. On the other hand, they might do it as a small celebration after a successful hunt.
And again, I don't know, it's
my opinion, please don't hurt me. Another thing I noticed is that, well, C-Hunter in Predator 2 seemed like he was kind of high in some parts of the movie. I don't know if anyone else noticed this; tell me if I'm wrong, as I haven't seen Predator 2 for atleast a month. I'll be sure to watch it again sometime soon...