Bests & Worsts Reviews from Amazon

For starters, I am new to this, but am very motivated to learn all I can about edible and medicinal wild plants in my area. I think the subject is great, and I have much to learn. In reviewing this book, I give it props for photos and identification information. However, after that, I was left less than informed regarding the usefulness of each plant based on applicable and relevant data, and as importantly, how to compare what is recommended in this book to medicines, salves, or food/drink that is common, should I want to consider an alternative food or medicinal solution. For instance, some pages reference making a tea using a certain plant, and will state something like "take 1/4 cup as needed". Hmm... I was left to wonder. Why not drink a whole cup - or 3? How much plant is used to make the recommended 1/4 cup? What contents would suggest limiting ingestion to a 1/4 cup? What could I compare this solution to, or what would it normally compare to or could replace, based on what is commonly found in cupboards and medicine cabinets? If to be used as a pain killer, what is the actual active ingredient(s)? Can 2 oz of bark from tree "x" provide similar pain management as 80 mg of NSAID? Are they the same (or similar) ingredients? What about vitamins and other common nutrients. Can these plants support what I need based on recommended daily micro nutrients? In looking up the apple, it gave no caloric, nutritional, or vitamin information. I was hoping to at least get a general statement regarding which plants could provide "up to x% or certain nutrients, or "provides x grams per x measure". I was really hoping I could learn about the WHAT, the WHY, and HOW in this book, as I live in the area the book covers. Unfortunately I got only some, and not enough to offer a basic understanding of how these plants could benefit me AND in what measure.