1963 RCA receiving tube manual, ... Are these useful for tube theory and practical (self-taught) instruction?If you have copies of any earlier RCA Receiving Tube Manuals, you will find that most of the material towards the front (covering basic theory and circuits) will be copied from earlier manuals. Therefore you may not see more in the front that what you've already read before (again, if you've got a copy of earlier manuals). There may be some additional stuff regarding television circuits, but on the whole perhaps nothing too useful.
There's also a catch with the stuff in the RCA manuals: it really helps to have someone who knows their stuff discuss the material with you. What I mean is the info that's there is factual and correct, but if you already know it inside out, then you start seeing how they put a lot of info in but also implied a lot of things. In other words, once you already know what they're already talking about, you'll see that they cover a lot, but if you don't know what they're talking about you might not grasp all they're telling you.
I have not read the Rider books, but anything by Rider covering basic electronics is a solid bet for you. Check out
Pete Millett's Technical Books Online. Rider's Inside the Vacuum Tube is a great book for those starting to get a handle on tube stuff. And Rider's stuff in general seems to be written in a manner that is easily grasped.
I'd get the whole set if I were you. I'd also consider contacting Pete Millett and giving him the chance to scan these books and post them online for the benefit of a wider group. I do prefer reading an actual paper book rather than reading it in acrobat format, but I'll also admit there's a lot of stuff on his site I'd have never seen any other way.