Hunting of animals

No, murder is defined as a human killing another human. Animals are fair game.
No, it isn't. "Murder" is defined as the premeditated killing of another of the same species. An animal's ability to feel pain or emotional stress has no bearing on the matter at all, distressing as it is to contemplate.

"Slaughter?" Yes. "Killing" is also acceptable and accurate, but not murder. The term has been misappropriated by people who want to humanize animals and demonize those who hunt them.