YES, horribly, deliberately, extensively, sadistically, and with an attempted justification later on of "for the greater good." Definitely skip this book if this is a trigger for you.
A pair of lions are captured from the wild and taken to a private enclosure, for the enjoyment of a rich, foolish celebrity who likes to taunt them and humiliate them.
Again, YES, horribly, graphically. This is a key scene in the book. A child is "punished" by being locked into a large charcoal barbecue and burned to death, which, due to his magical strength, takes an entire day. Other children are forced to help and watch. The scene was absolutely nauseating to read.
The fireball only gets to maybe a hundred meters or so in size before somebody stops it and then makes it shrink back down to nothingness. Yes, there's at least one character in the book who operates at that level of power.