This post is mainly in aid of recommending the book 'Catalyst'; this is a story based on the events that lead in to Rogue One, and for people like myself it is a must read. The new cannon has been pretty consistent and the books range from good to excellent. This book leans more to the excellent side of the spectrum. The background to some of the main characters, like Director Krenik and Gailen Urso, are of particular interest and Krenik in particular is an incredibly brilliant villain. I can't recommend this book enough, and in fact I would stress you get the Audiobook version with all the production value including sound effects and music!
You can get the book free as part of an Audible audiobook trial using the link I have active with my podcast: www.audibletrial.com/machogrande