Reddit mentions of Stride & Swing Piano: Hal Leonard Keyboard Style Series

This is a good book for both theory and the technical aspects of ragtime and then goes into other styles that use stride. Most if it will still be relevant to rags from a technical perspective. The music theory behind rags is ridiculously simple. There's really just not a lot happening harmonically. It's about as cut and paste as modern pop. Not that that's bad thing, but that's just how simple it is.

It's mostly I, IV, and V^7 with a bit of color from iv and bVI as well as diminished passing chords.

The more interesting thing is how rags evolve from and apply interesting polyrhythms from West African drumming to create a fairly straight ahead stuff that fits in a more Western music straight context via interesting syncopation.

Anyway, that book is great at explaining all of that and giving good practical examples as well as exercises. It then gets pretty deep into intense stride styles used by people like Art Tatum which is not for the faint of heart. John Valerio is awesomely thorough but he doesn't give a shit that you don't have a 10th or 11th. He's going to give it to you exactly as it was done historically even if the majority of people won't be able to pull off some of those technical feats.

As for collections of I rags, I don't really know of any particularly good collections or editions so I too would love to hear of some from someone who is more familiar.

I suggest getting this. It helped me a lot.
http://www.amazon.com/Stride-Swing-Piano-Leonard-Keyboard/dp/0634046632?ie=UTF8&*Version*=1&*entries*=0