No fat jokes, but the ladies are overly concerned about eating carbs and 1 character only reluctantly eats 1 bite of pancake. To me the depicted fear of getting ever so slightly fatter is no better
Yes, it was once, did not look too hard, during a heated verbal altercation, and it was between similarly aged girls. If that eases it for you, you can watch safely
Yes, 3 people are burned alive at the end. One of these 3 was completely on conscious. Also a short flashback of another from the earlier movie is shown as well