Tsukasa's facial expression is the only one I get.

Ralen said:
Tsukasa's facial expression is the only one I get.

The way I see it, Kagami is kinda mad 'cause Konata is pwning her ass at vidya (perhaps she has objections about the legality of Konata's way to play?)

Miyuki is trying to calm them down so the animosity don't escalate into an actual conflict.

Something like

-"Hey, that's cheating, Konata!"
-"I should be allowed to start the race first since your car has a bigger front!"
-"Now, now... you don't have to get mad, since Konata is only kidding"

pantyhose with shorts?

oh how i love you tsukasa

Pantyhose and shorts are actually pretty common together.
She just wears them particularly... cute?