I haven’t started reading this week’s part, so I might miss things
上から見る means in English “to look down on people”. Actually, thinking of it, that’s almost the same expression in both languages, interesting…
Anyway, assuming it’s her talking and based on previous interactions, I’d say she is talking to Subaru. She was annoyed at his superior attitude, and she finally understood where it comes from (あれなのよ; that’s it = that’s the reason). He is just too dumb to understand the situation. (The “unfortunately” here isn’t a literal 残念, it’s just a roundabout way of saying “bad”).
I know the fox sign. It’s pretty common. These days, it has a Baby Metal kinda feel to it, I guess.
About the frog sign, I know boys in the 6~10 yo age range like to make it. It’s really easy too:
I don’t think it has any specific meaning or anything; Subaru is just fooling around as usual.
Not quite. You are obviously thinking. Thanks to that, you can spout things out in a way that looks like you are not thinking.
Let’s break down the next one:
八方ふさがりで blocked from every direction (you got that one)
死ぬか生きる die or live
の瀬戸際で、on the verge/tipping point (and/connective)
[As if,] blocked from all directions, at that tipping point between being dead and alive
(The “as if” comes from the next part of the sentence)
腹の中身が the inside of your abdomen
ぽろっとはみ出してようと、as if it flopped out
while the inside of your abdomen are flopping out on the floor.
Combining both: As if, blocked from all directions, at that tipping point between life and death while the inside of your abdomen are flopping out on the floor
考え抜くのが人間の義務なんだから
Thinking it out is a duty, as human being. (It being the first part of the sentence)
Then ロズワール replies that “It somewhat gives me the feeling that you have really experienced having you insides flopping out on the floor”
Okay, sorry, I don’t have time to break down this one, so I’ll just translate it 
“Becauuuuuse the harsh truth is aaaaaalready known all over town!”
“Is that so? (さよけ = さよう+っけ in kansai ben) Damn, a (my?) dangerous secret has been known (= spread/spilled out), so I guess that development means I can’t go home alive”.
… I was just thinking “wow, it’s refreshing reading something easy after 新世界より”, but I guess everything is relative.
) then “Blocked in every direction, the critical moment between death or life it is the role of human to think deep inside. It seem that inadvertently I made true feelign come out.”
