The phrasing makes it seem like Yik Yak itself is not being acquired. Is that a thing that ever happens? I doubt square is interested in their tech anyways. I've heard that the Atlanta tech scene is dominated by business types rather then techies. It wouldn't surprise me if leadership is selling off most their engineering team and planning to outsource as needed from here on out.
Yes. If you acquire a company, you assume all their liabilities as well as the assets. You might want to just buy the assets and have the acquisition owners dissolve it themselves to keep the liabilities at bay.