Boot: Mike
He "needs to make a big move," and the game respects big moves. The game also respects numbers and logic, and really, this is the most logical choice.

(I'd also accept "Steve" as an answer)

Eliminated: Sarita
Even if it wasn't a foregone conclusion now that Matt returns, and that Sarita already won her million dollars with Russell's defeat, we had the "I spy..." photo capture of Matt helping build the new shelter. It's almost cheating to say Sarita loses.

Merge Name Creator: Rob
I theorized that Rob created the name as an homage to former Red Sox utility player (and Nomar BFF) Lou Merloni, who was frequently shuttled between the majors (in Boston) & minors (in RI) (Murloni = Merloni?), known as the "Merloni Shuttle." With no other found Spanish word for Murlonia out there, it seems just as good a reason as any other.

Individual Immunity: Natalie
Natalie seems the safest choice to win based on the promo pics (waitress + dancer = good balancer), but what I really liked was someone's idea that she gives her necklace to Rob. That'd be "jaw-dropping," but not too jaw-dropping, since they're both essentially safe (Jeff is prone to hyperbole)

Ralph Plays the Hidden Immunity: Yes
What'd be the cherry-on-top after having Rob get individual immunity (from winning or from Natalie), kicking out the biggest threat on Zap (Mike), and bringing Matt back under control? Getting rid of the other team's "hidden" immunity necklace! The stars are aligned on Rob's redemption this season, so why not give him something extra to talk about next week?

New Hidden Immunity Necklace at New Camp: Yes
...and why not just say "Rob finds the clue to the new necklace during the merge party," too, for good measure (he can find it next week... to give him something to do, and something for us to watch, while they pagong Zapatera)