I'm just going to put this whole post in spoiler tags because it's hard to tell what is and what isn't a spoiler. (If you haven't seen the whole series by now, though, should you really be reading this thread?)
They never say that Frank Lapidus is a candidate - they simply say at one point, "Do you think he's a candidate?"
Vudu, I agree that there's no real reason for Hurley to have won the lottery, other than the universe "self-correcting" and making him win the lottery with different numbers. There are some other similar "plot holes" that I don't think will really get filled. For example, neither Hurley, Claire, nor Locke really have any reason to be on Oceanic 815. Hurley was originally there to find out information about the cursed numbers, but if he doesn't have the cursed numbers, he doesn't have that reason to fly to Australia. Claire was flying to LA on the suggestion of that psychic guy, and they later figured out that the psychic guy put Claire on that flight because he knew it would crash on the island. So if Claire wasn't going to crash on the island, he really had no reason to put her on that flight. And finally, Locke was in Australia on a walkabout, and he originally got the walkabout idea from that black guy who was Whidmore's assistant. I think the assumption is that the guy told Locke about the walkabout because he knew that would eventually get him to land on the island, so if that wasn't going to happen, he wouldn't have told him about the walkabout. I highly doubt any of these things will be addressed, and they're ultimately not that important, but it's interesting to think about.