Well if you are interested in every aspect then I'd start with a good strength and conditioning textbook and a basic kinesiology text.
Essentials of Strength Training and Conditioning I highly recommend. A slightly more basic text is Conditioning for Strength and Human Performance.
For kinesiology there are lots of basic texts and most of them should be adequate. Manual of Structural Kinesiology is very good and basic.
If you go to googlebooks you can get snippets of all of these. The table of contents for sure. They got sued and derservedly so, imo, but now they are a bit more legit and are providing snippets in cooperation with publishers...so they say.
You should be able to get a lot from these without having a whole lot of prior knowledge. Coming at it with some fundamental knowledge of training and anatomy will help. But these texts are about the big picture...a foundation and background. I want to stress that it is a commitment and I don't want people to think that if they purchase any one book from my list they will come out of it with all the answers, lol.
A lot of people are tending to START with things like Science and Practice or Supertraining (which I purposely left off my list) and what happens is you get people with a boundless enthusiasm for arguing theory but no real fundamental experience in training...no bread and butter philosophy.
Oh, and tried to get your books used. Amazon usually has them used. Don't worry too much about the "latest" edition of stuff. While sometimes books like this are updated with chapters added or what have you, most of the time the "new" edition just has a new introduction or preface. Before you decide whether you need a brand new one...you should be able to investigate just WHAT is new about it. Most of my books are used.
BTW...a nutrition textbook. I really like Understanding Nutrition but there are lots of good ones. I think everyone should have a nutrition text...and I don't mean a "mass consumer" one. Something you'd find in a university bookstore is what I mean
. This will help you cut through a lot of the crap from "second-hand" resources. Used textbooks can be found affordably online. I mentiond amazon which is obvious. Alibris UK is probably the best place to search. I picked up understanding nutrition for free and it can be had for a mere few dollars, in some cases, on line...plus shipping. WELL worth it
It's actually baffling to me that people will spend 40 or 50 bucks for a "diet" book from some bodybuilding writer yet now shell out a couple bucks for a good textbook.