Were the Bantam reprints in chronological order? Would Bantam Doc #1 contain his origin? (How'd he get that way anyway, was his condition congenital? Or did he fall into a vat of chemicals like the Joker?)
That's a question with a lengthy answer, at least to answer it fully. No, they are far from being in chronological order (some of those in the '20s in the Bantam edition, for instance, belong close to the end of the run of the magazine, and there were 181 -- 182 if one includes
The Red Spider -- of the original stories). If you are interested, let me know, and I'll send you a list of the stories in order of original publication. But yes, Doc's "origin", if you will, is certainly dealt with in
The Man of Bronze (the first of the series in both instances), though it is covered in brief throughout the majority of the series as well, for the benefit of those coming to it through later stories. It also provides the set-up for some of the stories, such as
The Land of Terror (the second of the original set, #8 of the Bantam reprints) and, to some degree,
Fortress of Solitude (and yes, this is likely where the creators of Superman got the idea, if memory serves).
The same publisher also published the Shadow books?
To some extent. Bantam did a reprint of several of the Shadow stories, including the first (
The Living Shadow) and one of my personal favorites,
The Eyes of the Shadow, which has a particularly eerie storyline. Paperback Library tried to revive the series in the 1980s, with a much longer run, but even that scarcely touched the full run of the magazine, as you can see:
https://en.wikipedia.org/wiki/List_of_The_Shadow_stories
There have been other attempts to reprint the series, but I don't know of any which have managed the entire set. However, I'd certainly love to be proven wrong on this....