Jaw spreaders are cheap: https://www.cabelas.com/shop/en/bass-pro-shops-fish-mouth-spreader
https://www.cabelas.com/shop/en/tyrant-tackle-jaw-spreader
You can spend more, but those will get you going. Hooks with crushed barbs make it even easier - I can usually unhook pike, and most muskies, without taking them out of the water.
...for leaders, I just tie tieable wire into my main line.