Regarding the konpeito thing: I think the goal was to cute-ify her "bullying" into not being 100% bullying, so I probably would've replaced konpeito with Lego as "a thing which hurts to step on."
... Unless, of course, kids have actually moved onto konpeito from tacks for actual bullying, since it's a lot less suspicious to carry candy around and you could maybe argue it down from "bullying" to "nuisance" in case you get caught. I still think the first case is what was at play here, considering the overall tone of this manga.