IMO Brent sucked on purpose two rounds in a row to get his two teammates kicked off. I feel 99% confident that is true at least with Brian, who was bringing that team down significantly. Brent knew if they lost the immunity challenge, Brian would be the chosen player to go head-to-head, and likely lose and be kicked off. He was spot on. He then probably saw Stephanie (I think was his other teammate) as a weak link, and there was probably a 50% chance at that point he figured they would pick her head-to-head as well. Then it would be only him and he would feel more confident alone than with iffy teammates moving forward.
I think the actual competition lasts maybe 1-2 weeks. Every show the players hint at "we'll see what happens tomorrow," but the show isn't aired for another week. I hear that clue on every show, so I have a feeling they weren't in Mexico for more than 15 days, grinding it out every day until it was over.
I think Stephanie was one of the best players on the show, let alone the best female. Lebelie and Taylor have played very well lately, but I still think Stephanie is the best female. I'd put the chances of him tanking it at more like 5%. He's just a bit overrated due to his strong performance in one of the challenges. He established a reputation he wasn't going to be able to live up to. I fully expected him to struggle in a few of the challenges he did. He's still just a human golfer.