Do you think that Rainsford would have taken Zaroff's (or general) place and continued to play the most dangerous game?
No way, Rainsford was opposed and disgusted by what Zaroff was doing. He would immediately dismantle all the traps Zaroff set up to lure sailors to the island. He would probably set fire to his chateau and all evidence that Zaroff was ever there. He would take one of Zaroff's boats and sail back to civilization. Whether he would never hunt again is another question that I'm not so sure about.
I think it is clear from the conversation that Rainsford and Zaroff had together that Rainsford is just not able to justify the use of fellow man for "sport" in the way that Zaroff was. Zaroff based his actions on the justification that if you are more powerful than another person, you are free to use that person for your own pleasure - even if that means killing them. Zaroff saw no distinction between man and nature and killed all who were weaker than him. Rainsford definitely does.
This is a very good question. No, I don't believe Rainsford would continue on in Zaroff's hunting habits. Someone would have to be insane to do what Zaroff did, and it's not likely that Rainsford was just as insane.
I think not.
Rainsford is an amazing hunter in his own right, but he recognizes the horror and inhumane quality of hunting humans.
He is shocked as Zaroff explains what he does on the island, and even more shocked to learn that Rainsford himself is considered to be a worthy prey for the General's entertainment. While Rainsford and Zaroff have much in common, the one thing Rainsford has that Zaroff does not is his sense of ethics regarding honorable vs. dishonorable hunting and kills.