When did Nozomi ever refer to Nico as anything but "Niccochi"? "You're one to talk" would definitely suggest the student council in my mind, so that just leaves Eli(especially given the calm nature of the comment).
Youmu and Reisen are both making possessive faces. Reisen giving the common "she's mine" look to the camera, but Youmu giving a "you're mine" look at Reisen. That definitely suggests an interesting dynamic between the two.
I think Youmu's expression is softer than it first appears, it's just her head being tilted down relative to the viewer makes it look like she's frowning a bit.
Homura has been hurt over and over again. She's dealt with feelings of frustration, disappointment, guilt and so on so I can't really blame her for doing what she did in Rebellion.
@Prince_Anime
Her armour is far from shining, but that's not a bad thing:
A knight in shining armour is a (wo)man who has never had their mettle truely tested.