Good luck with your interview Jenny! I also have an interview this week, but for a postdoc position, so I'm preparing too!
That thing with the article is strange, I've never heard of that before, but it seems to me you are on the right lines. I think you should read other things from the lab too and generally about the research area of the PhD.
Ask them about what other students, postdocs etc in the lab, possibilities of small group teaching, demonstrating etc, training for PhD students, conferences etc