They can be ferocious if cornered. Mean little chits, I can tell you that. They don't play well with others, and tend to very aggressive toward other, larger animals. While most of the stories you hear about them are exaggerations, they are very powerful and a dang handful when cornered. They are smelly animals and in the weasel family. Can get to 12 to 16 inches tall and up to about 3 feet (1 Meter or so). They are a grand trophy and make a gorgeous full body mount. The license to take a wolverine is pretty cheap, and I would have a tough time transfering a much more expensive license to the animal.
I don't think they kill for the sake of killing. They may kill while having another food source nearby, but would imagine its for teaching the cubs how to kill or for caching food for future use. Wolverines have a tough time. They aren't very fast due to their short stubby legs. They have problems in deep snow. They are scavengers for the most part, but will lie in wait for prey to come by.