ARRIVAL/ When do Bobby Jon and Stephenie show up?
The official cast photo on the CBS site (copied below) shows the 16 new castaways in their tribal buffs. ET's preview shows the blue tribe is named Yaxha, and the first TV ad confirms the second part of Dan Bollinger's spoiler: the yellow tribe's name is Nakum. So, as far as the usual Ep1 surprises and/or twists go, there aren't many left. Except of course for the two returning players, Bobby Jon Drinkard and Stephenie LaGrossa, who appear neither in the Day One cast photo, nor in CBS's press release. (These two would be the "two twists" the TV ads are referring to). So the only real mysteries are when these two show up, which tribes they're on, and what their role in the game will be. More on that below....
What we can see from previews and press releases is the two tribes, wearing their new buffs, individual Guatemalan-style bags, and canteens, filing through the ruins. Presumably, Probst will greet them there with some sort of official greeting, and disperse them to their camps, about which the press release claims: "The castaways will begin their adventure with a grueling 11 mile hike through the jungle." They're also there to take pictures, of course, but we're guessing that won't be shown.
We also see the Nakum (yellow) tribe, as threatened, living amongst the ruins. They are similarly- (largely just less-) clothed to their arrival pictures, and Brooke and Danni seem to be pointing a lot, perhaps during shelter construction. Smoke is visible at Nakum, so they probably have fire. Both tribes appear to have primitive blade tools, pots, and bags of what Corvis says is flour.
And last, but not least, we have the Yaxha (blue) tribe. The bulk of their camp vidcaps appear to come from at least Day 2, because everyone is wearing more (and mostly different) clothes than at arrival, and they already have their shelter built. And, oh yeah, they also appear to have an extra member. As pointed out by CSCin3D at Sucks, Rafe's interview video at the CBS site features a familiar-looking forehead and headband: that of Stephenie LaGrossa (right-hand picture, bottom right-hand corner). It's unclear how or when she got there (Day 1?), but she appears to be hanging out in camp at some point after the first day.IMMUNITY CHALLENGE - Canoe race, wok lighting/ Yaxha leading?
Not a lot to go on here yet, at least until the week of the premiere or so, when the various entertainment news shows, the Early Show, TV Guide Channel, and the TV Guide print edition start to have previews of the first episode. But the first TV ad shows a canoe race that is likely from this challenge. Furthermore, the CBS News video of Jeff Probst's cast assessments does show him standing in front of what could be the finish line of this challenge (rightmost cap).
Judging from the presence of a Yaxha color-coded wok behind Probst, this challenge may also involves fire-starting. So, presumably, in addition to the canoe race shown (at which Nakum appears to be trailing slightly), it could be that, after bringing the canoes back onto land, they must then light a fire in their respective wok (as in many other Ep1 ICs).
While we won't yet hazard a guess on the lucky first bootee, we will note that the TV ad also features the usual opening credits sequence of stand-ins carrying torches in the tribal council area. (Vidcaps at right). So from the looks of it, tribal council may be held in the shadow of a pyramid, which (assuming SEG didn't build a fake one expressly for this purpose) is at least moderately interesting http://truedorktimes.com/survivor_guatemala/spoilers/index.htm