About imperfective/perfective: No really. Why isn't anybody believing me? I've read tge chapters on this particular subject in several, different Russian grammar books and it's not that hard for me to grasp. Actually pretty easy if you ask me. To answer your question, the answer would be "She didn't read the book." stressing if she didn't read through it completely or she just didn't read it at all. Quite simple if you ask me, not to sound pompous or anything.

About cases: As much as cases seem like the most *enter 20 curse words of your choice here* thing in the history of languages (next to English spelling, and how we haven't had a modern spelling reform yet because we're too lazy), I have to learn them. Cases are needed for me to be understood, but that doesn't mean I don't think they're complete BS... because I hate them.