all I really noticed was lots of pages of the Justice League on what looks like Apokolips, and repeated scenes of an evil woman with a baby (Superwoman from Earth 2?)

I was gonna buy it but the only page that interested me was the spoiler of Batman telling Hal that he didn't get the Joker's identity because there are three.

I was a little confused though because I thought the issue would feature the REBIRTH Justice Leauge, but New52 Superman is featured in the story. But he dies to make room for the "real" Superman to come back. So...are the other New52 DC heroes the same heroes from the regular DC Universe who have just been living in their own timeline which has been altered, or are they separate characters existing in a separate timeline like Earth 2, Earth 3, Earth B, etc?

I don't think I'm going to be getting back into DC or Marvel any time soon. It's great they're bringing back the real Superman, whatever that means, but there's not much incentive to follow or care about what happens in the core titles since there's so many other avenues available to follow the further adventures of the DC Universe.

For Batman alone there's:
-The Batman Arkham games
-The new Batman film franchise starting with B v S, and Suicide Squad
-Batman Earth One graphic novels by Geoff Johns
-various Batman cartoons always airing (Batman Unlimited, Brave and the Bold, etc)
-Injustice: Gods Among US comic and video game

and probably a whole lot more I can't think of.

The only comic I'm following regularly is Attack on Titan. It's successful enough to have adaptations in other media, as well as some spin-offs, but I'm fairly certain that they're all based on what's happening in the manga. There isn't to my knowledge multiple official mangas out there telling different versions of the same story, competing with itself. The pace can of the manga can be frustrating at times, but the it's a pretty unique concept, and the title itself is relatively new, so it's a much more exciting read than what's going on in DC.