The outfits are never found, and it’s never revealed where they even got them, they just suddenly show up dressed. And about the Ikki scenes, you need to have the loli route active, and if it is, they’ll show up naturally. What got me "stuck" was not realizing that the “repetitive” Zhu Li scene actually wasn't repetitive, it just varied subtly up to a certain point, and only after that did it start to change.
BTW, just a detail: I’d honestly prefer it if Marty had drawn Jinora’s ass smaller than Oppal’s. The way he did it, the proportions ended up feeling way over the top