The two items you call out as possible bugs are, embarrassingly enough, working as intended although I can see how the UX at those points is sufficiently confusing that one might reasonably assume them bugs. For instance, the rating showing up for an article no longer rated - that is the predicted rating for the article. As you start to rate articles in a topic, we show the predicted number of stars for all articles you haven't rated. This can be useful to know (e.g. the ML learns the most from the manual ratings that differ from what it would otherwise predict). The visual distinction between these predicted ratings and your explicit ratings is that the star by the number is filled in for your actual ratings. So the UX problem is that there is no way to know that is what the filled-in / not-filled-in star means. Anyway, will try to improve this.
Amount of UI text is tricky. There is value in both clarity and terseness, and it's a balance I don't always get right.
The ratings are per-article, not per-story, so a rating dropdown guy for the non-primary articles of a story almost certainly should be added. Excellent point.
And sorry about missing the hearts over stars trend. We're hopelessly uncool. Hell, we still love c++.