At eNotes, it is preferable to answer only one question at a time, so you may want to repost the remainder of these. However...
1. Rainsford was stunned and bewildered at this monstrous proposal. He replied, "Hunting? Great Guns, General Zaroff, what you speak of is murder."
2. Ship-Trap Island is aptly named. Zaroff has set up a system of flashing lights that indicate "a channel where there's none. Giant rocks with razor edges crouch like a sea monster..." Ships run aground, and he and Ivan lure the survivors ashore before imprisoning them for "the game."
3. After rescuing the shipwrecked sailors, Zaroff gets them in hunting shape. "I treat these visitors with every consideration. They get plenty of good food and exercise. They get into splendid physical condition. You shall see for yourself tomorrow."
4. Zaroff gives his human prey a head start and then he stalks them. "It's a game, you see," pursued the general blandly. "I suggest to one of them that we go hunting. I give him a supply of food and an excellent hunting knife. I give him three hours' start. I am to follow, armed only with a pistol of the smallest caliber and range. If my quarry eludes me for three whole days, he wins the game. If I find him"--the general smiled--"he loses."
5. Zaroff wants to make sure that his "guests" realize there's no chance to escape playing the game. He may not tell all of his prisoners about the dogs, but he informs Rainsford. "They are let out at seven every night. If anyone should try to get into my house--or out of it--something extremely regrettable would occur to him."
6. Rainsford loves to hunt big game animals, but hunting humans is simply murder. Zaroff, the Cossack, is a barbarian; Rainsford is not. "Thank you, I'm a hunter, not a murderer."