The climax of Richard Connell's story is when Rainsford suddenly appears in General Zaroff's bedroom after Zaroff has assumed the Rainsford committed suicide (this is also irony). The resolution of the conflict between the two is when Zaroff is killed by his own dogs, and Rainsford gets to sleep in his bed.
When Rainsford is aboard the yacht, Whitney tells the story of Ship-Trap Island where sailors have gone, yet never returned. This foreshadows that Rainsford is somehow going to end up on this island so that the reader learns the truth of the tale.
When Connell writes, "the sea was as flat as a plate-glass window", he uses a simile to create a visual effect in the reader's mind. This demonstrates just how still the water was at that point.
Suspense is created through the various traps that Rainsford sets for Zaroff, yet the general manages to escape them. Each time he escapes, he comes closer to capturing his prey-- Rainsford.
As for personification, Rainsford says, "Who cares how a jaguar feels?" to which Whintey replies, "Perhaps the jaguar does."