we also have to conclude to some degree that after Ace was voted out and they returned to camp expecting to merge the next day, that a lot of strategy was discussed. Ken says they can be the final four. Most likely, they stayed up and thought of some plans when they thought they were going in 4-6 and how to get Dan or Susie over, or how to use Sugar's idol as a foursome to weed out the numbers. A plan was hatched, and then derailed when they swapped, but probably communicated again when they did finally merged (at least from Sugar's vantage point) -like when Ken and she ran off into the woods, they were probably talking more than just "vote Charlie" but "okay, remember our plan..."

the fact that she said she didn't trust Crystal and Ken doesn't mean anything (except only included for a plot point down the road) -surely, every contestant has to run down the list from the confessional interviewer where they ask them the pros and cons on every other player. (Charlie probably received questions on Marcus where they could get a sound byte of doubt if they needed it)

Yes, the dominating tribe is the safest strategy and no one is going into the game hoping they're on a tribe where they lose. But sometimes it's out of your hands -can we fault someone like Susie getting cast on a show with Marcus, and then say she's a bad player because she can't carry a two ton snake? Okay, she can't do that -so she better wise up and think of a way to stay then. etc. etc. etc.