いっぱい - See definitions 3-5 on Jisho. It means full, to the maximum, a lot, things like that. I’m not sure how streetpass works - if it has an upper limit I assume she’s reached it. If not, then she got enough passes to be happy.
気持ちがね - I’m not sure. I think that it might be 気持ちが悪い with 悪い omitted. Or it might be just an appeal to them to show some consideration for her instead of just celebrating their streetpass success.
Although there is a limit on the number of StreetPasses one can have queued up, the limit’s low enough that she would have been able to reach it at the station. You can retrieve the StreetPass items in a game to open up space for more StreetPasses, which Kotoha would have to have done considering how long the two are at the gathering of 3DS players.
With this gaming knowledge, I take いっぱい to mean “lots” as in she received lots of StreetPasses.
(As someone who’s been both staff and vendor at various comic, gaming, and anime conventions, I know exactly what it must have been like for Kotoha going through and clearing out the StreetPass queue, only to have that green LED repeatedly light up each time another StreetPass comes in.)
This one plays on すれ違う’s meaning of “to pass by one other” or “to miss each other”. Kotoha is saying she got a lot of passes, then Yui supplies the が-marked subject (the thing that was passed by) as 気持ち (Yui’s feelings). Consider that Yui is pouring her heart out about what she’s just been through, and Kotoha completely ignores her to comment on the StreetPasses.
Page 61, Panel 6, Yui
そうだね
気持ちがね
I feel like I actually got pretty close with this one. I didn’t get that Yui is marking it as the subject of Kotoha’s statement though, I just translated the そうだね as more of a “That’s true” and 気持ちがね as “But what about my feelings”.
Here’s my take on it:
Kotoha: “There was lots of passing by!”
Yui: “You’re right! [Passing by] my feelings!”
I’m still a learner though!
Edit: I just realized that I put feelings as the object rather than the subject here. I’ll have to rethink it when I have time later.
I feel like I is the part that I got the most wrong. I was so stuck on the surplus meaning of 余裕 that I assumed she was just excited about the large number of people playing Streetpass and the surplus of stuff she would be able to get there something like "That much surplus. Where is it?. Reading the chapter again it seems more clear that she reacting to Saitou telling her that it is 20-30 minute walk way, and that is too far for them.
No, Saito thinks it’s too far. Kotoha thinks that it’s not far at all, considering she can play her game at the other end.
Ah, I was off. I interpreted it as Saitou was just saying it is too far away for them in order to goad them into going “far away” to give him break from them. I am a still at the point where even if I know every word in a sentence and the grammar being used, I can still miss a lot of nuance.
I also interpreted it this way, since Saitou has a sneaky sort of expression on his face.
Also on the next page in he is laughing and saying something like “I drove them away from this town”
Saito does say it’s too far a walk for them, and he says it in such a way that they will want to contradict him and take up the challenge. He does in fact intend to send them far away, and Kotoha reacts in just the way he expects her to, by replying that this far isn’t really far at all and immediately setting off. Saito is happy that the girls left his patch, the girls are happy because they do get lots of Streetpasses. The only unhappy one is poor Yui, forgotten in the park.
So I wasn’t far off in my interpretation of events. I really more missed how Kotoha is using 余裕 in her response. It was a new vocabulary word for me so I just went with the first definition of surplus and then tried to figure out how to make that work contextually. It sounds like it is rarely used to mean a literal surplus of something such as Mii Streetpass players. And much more often to mean sort of an excess of anything, in this case too much distance for Kotoha and Satchan to cover. At least when I run into it in the future, I will have this definition in my mind.
I found this week a bit harder and have several more questions beyond what was already covered:
Thanks for the help as always!
ちょうだい is essentially the same as ください. “Please give me that game”, basically.
She’ll shout to get someone else’s attention if she doesn’t get what she wants. Basically “gimme it or I’ll scream”.
Casual speech casually shortening the vowel.
格好 also means “appearance”. Like, her clothing. “What’s with that get-up?” sort of thing.
Reckon it’s more like “Just where do you think you are?” (A question she answers herself in the following panel on the next page.)
The second line is a question - are you a shy person?
I am still playing catch-up, but I am confident, i’ll be current soon… This chapter was quite hard for me! I think it was the most challenging I’ve read so far! I still have two more questions, which were not yet answered, again if anyone is still willing to answer, I’d highly appreciate it! 
Thanks!
Page 56
Although we see these straight-sided word balloons with big, bold (loud voice) letters in them from all three girls at various times, Sacchan’s the one most likely to be shouting randomly. The inclusion of the 「あははは」 (characteristic of Sacchan) between the two suggests it’s her shouting (and laughing in-between).
I think it’s because she doesn’t really have a concept of what 「すれちがい広場」 is, and they’re following a narrow (狭い) street to get to this “wide” (広い) place.
Page 61
Yui first corrects Sacchan that the saying is 「灯台もと暗し」, meaning it’s darkest under the lamp. Then she applies what Sacchan and Kotoha did, saying if you go too far from the lamp, you also can’t be seen. In other words, while Sacchan was going for hiding right in front of Yui by being behind the tree where she was counting, she ended up hiding by going beyond the bounds of where she could be seen.
Now she’s linking it back to their current predicament - i.e. if the lamp post is in Ueno Park, and they go to Akihabara, there’s no way the light from the lamp post will reach that far.
I wonder whether it’s some sort of pun based on the ちがい part of すれちがい. Is it 広場, or ちがい広場, which would make it, I don’t know, 狭場?
FWIW, I thought along the same lines as you, that it was sort of a pun on that. Certainly not one that could be translated all that well, though.
