Pappy, I agree 100%, Grandfather's Attic is another great tinplate book. It's a little more focused on O gauge tinplate, but still very worth the investment for background info. His section on restoration in that book is excellent if you're into that at all: when to restore, and how, and when not to.
The photos Riddle uses are very helpful in comparing and sorting out the different manufacturers, couplers, and even the different sizes of Standard Gauge made by one manufacturer like Lionel.
The third book that I think of with these two by Riddle, is "Classic Toy Trains" by Gerry and Janet Souter. This book really takes in the whole sweep of the various manufacturers and how things evolved to the state we're in now. The Souters have a wry sense of humor that makes for terrific reading. And again, the photos are really helpful.
I was brought up reading books so I always devour what is out there on a subject I'm interested in. Of course, there can be wrong information in books too, but when the research has been done right, you can learn a lot.
Then of course there's the likes of Louis Hertz' "Riding the Tinplate Rails", if you really want to read the classics. But that's another trip altogether.
Sunrise, I was brought up running my dad's Ives standard gauge trains, so I have a built-in bias toward a certain manufacturer and period as to what looks and feels "right". I don't think I'll ever warm to Lionel with the same connection I feel toward the old Ives. If you're starting out more neutral, that will be a benefit, you'll be able to look at all of them and decide what characteristics you like in each.
And compatibility is really not a problem. You'll see many examples on these forums where folks have just switched out couplers to run one makers' freight behind another's loco. Others have made custom transition couplers to hook unlike cars together. It's easy to do, and there aren't any rules to break.
After Ives, my favorites are McCoy, which took me totally by surprise. I didn't even know about them until just a few years ago, and the trains are much more toylike than the more realistic Ives. But I just love them, they are the coolest thing. Who knows, maybe you'll develop a passion for Dorfan or Boucher.