To be honest, I don't think there is one "THE book to read." They all do a very good job of explaining the process, but they each word the explanation a little bit differently. Sometimes just a slight rewording really helps describe something better, but this is entirely subjective. What might be as clear as day to you, might be clear as mud to me.
It is nice to have the manual for the exact components you are using, but isn't essential.
The reloading tool maker's books are good, because they aren't tied to one brand of bullet or powder, but be forewarned, Lee sure lays on the hard sell pretty thick. If you don't use his tools, you paid too much, you're ugly, and your mother wears army boots. Too bad, because I quite like his writing style and his description of the process.
The ABCs of reloading is a staple of most reloading benches, and as it doesn't have any reloading data, and isn't written by anyone trying to make a buck off of you buying their stuff (other than the book), it is a great resource.
Be very leery of youtube. The majority of the vids are from folks showing off their reloading prowess that they have acquired from the twenty rounds they have made today. I also have a hard time listening to someone trying to edumacate me when there is an unending stream of "umms" and "uhhs."
Read lots, don't believe any of it until you find it corroborated elsewhere, and don't be afraid to ask questions.
