Also, how does DC rebirth affect the continuity of green lantern?
As with almost every reboot, there is almost certainly no set list of what is in and what is out. Until something is explicitly mentioned as having happened in a book or some other canonical source, the answer to the question "did this happen?" is almost certainly "maybe". It will take one writer or another deciding that they need event XYZ to make a story make sense, or contrariwize they need event ABC to go away so he can tell his story.
Rebirth, as with the story Green Lantern Rebirth from which it got its name, seems to be doing a good job of not quite restarting everything from scratch, but "revealing" that certain facts and assumption are not true, and that certain new events help fix problems of the past. Example - we learned that Hal Jordan did not in fact kill all of those Green Lanterns, as opposed to changing history so said event never even happened.
So far there have been no major changes to the origins of most heroes (Wonder Woman is going through a bit of an Everything You Know Is Wrong moment), just changes in mindset. So no changes to the GL history, recent or long term. Same for Batman, just a number of bat-characters returning to working with them.
It's not as much that it's "a mess" as much as every plot thread set up in the launch book has been picked up yet. We probably won't see much mention of the JSA or the Legion until next year, once the get the main titles on an even keel.
And let's just not even talk about the whle Watchmen thing at all, eh?
When they get the ten years that were stolen back, things will start to fall into place. Wally said in Rebirth that it wasn't Flashpoint - it was longer ago than that; I think 1986 post crisis beginning was when it got dark, hence Wally saying they changed. Watchmen ended same time as Crisis of Infinite Earths, it's pretty eerily convenient.