Spend time on the colored charts; these are the "cheat sheets" for the entire unit. Complete Exercises in Order:
A: Yes, but PDFs are not reflowable. Convert it to Kindle format (MOBI/AZW3) using free tools like Calibre, or simply use the "PDF viewer" mode on your Kindle Fire or Paperwhite (though text may appear small).
Before starting a unit, look at the introductory images to understand the context (e.g., "At School" or "My Family"). Focus on the Grammar Chart:
Once you have a legitimate copy of the PDF, simply reading it on a screen won't teach you grammar. You need a strategy. Here is a 4-step study plan.