Who is the narrator, can she or he read minds, and, more importantly, can we trust her or him?
Varies
Each chapter has its own narrative technique. For example, Chapters 1, 5, and 9 have a third-person limited omniscient narrator that focuses on Dedé. The chapters where Minerva and Patria are the narrator (2, 6, and 12 and 4, 8, and 10, respectively) are told from the first person perspective, with each sister telling her own side of the story. Mate's chapters are also written in first person, but they are in the form of a diary.
The Epilogue (Chapter 13) is from Dedé's perspective, this time in first person, and the Postscript (Chapter 14) is written from the author's first-person perspective. So, yeah, like we said—this novel employs a veritable smorgasbord of various narrative techniques.