They’re talking about buying the happi for the festival, I think.
Yes! Next seems to be a 風香 chapter. 
すっかりやさん? ADHD, huh?
What a mood.
Don’t smoke, kids.
And, yeah. After reading, I think it’s implied that she doesn’t know how to read デ and thinks it’s ド. 
You’d have to have no heart to think it’s a problem for Yotsuba to sit with you. 
やるじゃん！
Never mind. 