I just use regular scissors. Depends on how big the cc is. If it's a small one, I cut most of it, since the center (mouth) is the main organ. If it's bigger, I would cut half that leg and then move to the next leg so the one I just cut would heal. It's true that when you cut a leg of any seastar, they would regenerate, but let's just say, you cut only half the leg and then the rest of that same leg next week or something, the cc doesn't have enough time to heal and sometimes it dies, even if you attempt to feed it, so it would heal faster.
Like Gluestick said, you can have more than one cc to let them regenerate their legs. I tried that and combined with feeding the cc, they still regenerate really slow. IMO, you would need to have at least 10 cc's and if you had a pair of these, double that
Yea, I have a couple fellow reefers that wouldn't dare cut a cc

Once I drop in the leg, the harlequins will pick up the scent and try to "hunt" for this. If there's no bigger fish to pick on them, they'll just hang out in the open. If not, they will just find a cave or something to stay cover, but you'll still be able to see them, unlike pistol shrimps.