Aight, let's see...
For Blackest Night, you can read the three titles PB's talking about, and be cool with it. But if you're interested in The Flash, I think Blackest Night: The Flash is an amazing tie-in which explains alot of in-universe stuff.
On Brightest Day, it's not really a question of following everything. See, the repercussions followed alot of different stories, but you don't need to read any of which characters you don't care about. For Brightest Day, you follow Brightest Day. That's it. But it's by far NOT a Green Lantern book, aside from the White Lantern being on everything. Green Lantern itself deals with a completely different story which concerns the entities far more than the White Lantern, and follows with its own plot, completely independent. While Brightest Day is a Rebirth book for Aquaman, Deadman, Hawkman/Hawkgirl and Firestorm. Just follow it at your own pace, because the only thing that's likely to concern the GL book is the eventual fate of the white entity/guardian.
On Morrison... oh boy. My introduction to Morrison was the SAME THING. And I hated all of it. But I kept going, and eventually, I fell in absolute love with the man.
You gotta make a choice here. If you want to go deep into Morrison's writing, and actually understand the themes and style he's going through, Animal Man is the best introduction to his genre.
If you want to follow Batman, then start with Batman & Son. It's the start of his run, and then follow through with Batman: The Black Glove, Batman: RIP, Final Crisis, and Batman & Robin (reading return of Bruce Wayne when you get to the part when it tells you to). Reading the titles like this will give you a much better understanding for the whole story. And keep a notebook around you to write down a few themes you see, as well as stuff you don't understand yet. Because it all makes COMPLETE sense when you put all of the pieces together, and it's absolute genius.
In regards for Batman: INC, it's a whole new beginning for Batman, and the stories are basically Batman being James Bond. Being incredibly cool with gadgets and having a few shout-outs to the old wacky days with whole new villains and allies. It probably can be read on its own, although the underlying themes seem to be preparing for something big. The whole run up to the end of Batman & Robin was basically a worlds, times and dimensions-spanning war with [spoiler]Darkseid[/spoiler] that Morrison weaved through in the most brilliant way possible. The rest will probably follow through with it.
I can post you conspiracies, themes and all of the theories of the book that can be followed through all of the Batman books, and explain you all of the symbology present. But it's something you gotta choose if you're gonna follow, or quit. Because you gotta be somewhat dedicated with some of the themes to enjoy it.
The entire Morrison run