It seems odd that the UNSC would be so quick to try to use Kwan for propaganda purposes. Surely there have been plenty of other survivors of Covenant raids, even on Independent colonies, and some of them must have been willing to cooperate. Kwan claims that the colonies know not to believe UNSC propaganda, but that still brings up the question of why they thought it would be different this time.
However, she's the daughter of a famous Independent general. Her speaking out in favor of the UNSC would be a huge boon. At the very least, it would convince people that the Covenant are real.
Though, that assumes people are familiar with her, and that her testimony isn't being coerced...
Having Miranda Keyes try to make the appeal is also puzzling, given that by her own admission it's not the sort of thing she's got much experience with. Probably it was a token effort to get her on their side before they'd either have to kill her to keep secrets or pass her off to another one of UNSC's internal factions.
If the UNSC is actively fighting the Insurrectionists and the Covenant at the same time that would indicate their concern is spreading resources too thin and are trying to resolve the Insurrectionist issue as soon as possible. There was also a subtle implication that they tried to find the least intimidating person to make that proposal, and finding someone a little closer to Kwan's age might have had a better chance than an ONI agent or Admiral.
Spartans' senses being numbed to the point they can't taste anything makes sense. They're meant to be fighting machines often sent out on their own for extended periods. In such situations, it's better for them to be able to find nourishment from whatever source possible and not have to worry over whether something tastes good or bad.
At the same time, John's comment that he's not eating because he doesn't see anything he likes makes sense: Due to the sense- and emotion-numbing agents, Spartans probably don't derive any pleasure from eating at all, even if they understand intuitively that baseline humans do.
Soren remaining rebellious and charismatic post-augmentation probably means that the sense-numbing pellet in his back either malfunctioned or didn't take.
In "Contact," Halsey instructs Silver Team to protect John at all costs, while the UNSC garrison at Reach is gearing up to capture him. Kai asks if this means engaging friendlies, and Vannak replies that if they are going after Chief, then they aren't friendly. Fast forward to the penultimate episode of the season, "Allegiance," and Vannak and Riz are ordered by Halsey to take John down. Kai, who has since removed her Restraining Bolt, immediately goes toe-to-toe with both of them to protect John.
Doctor Halsey's flash clone, who becomes the basis for Cortana, notes that Halsey's view on sacrificing for the greater good feels very different when you find yourself viewing it from someone else's perspective. Cortana becomes very sympathetic to John's situation and turns her back on Halsey. During her final conversation with Miranda, Halsey tells her that she's only hurting herself by trying to live up to Halsey's expectations before being revealed as another flash clone. It seems that the only thing that kept Halsey from being far more sympathetic and supportive to those around her was the epiphany of seeing herself from any other perspective but her own.
