War of Kings has NOT started yet, seeds have been planted.
And in terms of Secret Invasion, I meant the Secret Invasion: Inhumans mini-series, not Secret Invasion proper. Secret Invasion itself is pretty much completely unnecessary in terms of understanding War of Kings. The specific lead-ins, as cited by Marvel, are as follows:
Secret Invasion: Inhumans (Which just wrapped up and deals with the Inhumans' lead-up to the mini)
X-Men: Kingbreaker (Which starts Wednesday and deals with Vulcan, the Shi'ar Empire and the Starjammers)
The current arc of Nova, starting with issue #19 (Dealing with Nova and Darkhawk's involvement)
The current arc of Guardians of the Galaxy (Dealing with their involvement)
As the story establishes, there are four Kings involved. Three have been revealed thus far.
For further reading, which would give background to how most of the players got to their current status quo, some good reading would be, for each set of characters:
Inhumans: Son of M, Silent War, Secret Invasion: Inhumans
Shi'ar: X-Men: Deadly Genesis, X-Men: Rise and Fall of the Shi'ar Empire, X-Men: Emperor Vulcan, X-Men: Kingbreaker
Kree/Negative Zone/Guardians of the Galaxy: Annihilation, Annihilation: Conquest, select issues of Nova and Guardians of the Galaxy
All the relevant info catching you up will likely be contained in recap pages, but if you've got some time to kill and just feel like reading something fun, that's the leadup.
Here's some basic run-down of the main players, major spoilers ahead:
The Inhumans: They're a race of super powered humans created by the alien Kree through a chemical called the Terrigen Mists. They live isolated on the moon, fearing normal humans. After the House of M storyline where 90% of mutants lost their powers permanently (An editorial effort to clean up the over abundance if useless mutants), Quicksilver, the son of Magneto who is also married to an Inhuman, went to them for help. They refuse to give him access to the Terrigen Mists, but he ends up stealing them. Eventually, the U.S. Government gets ahold of them and the Inhumans go to war to get them back. The Inhumans are eventually infiltrated by the Skrulls, one of whom poses as their leader Black Bolt. I'm not sure how this all turns out as I haven't read it, but I do know they recover Black Bolt and he will be one of the "Kings" in the event.
The Shi'ar: This one I'm more familiar with, as I read X-Men routinely. Vulcan, a mutant by the name of Gabriel Summers, appears on Earth shortly after House of M. He was part of a kind of X-Men 1.5, created between the original team and the All New team in the seventies. They were sent to rescue the originals from Krakoa originally, but all were presumed dead. It's revealed that Vulcan and Darwin (Whose power is to basically just evolve automatically to survive, not to fight better, just to survive) survived. Vulcan's origin is revealed as having been Cyclops and Havok's brother, who was born in Shi'ar space after their parents were abducted . After Vulcan learns the extent of his origin, he goes to Shi'ar space to destroy their empire (Followed by Xavier, Darwin, Nightcrawler, Havok, Polaris and Warpath). Over the course of the next twelve issues, he ends up marrying Deathbird, killing Emperor D'ken, his father Corsair and becoming the new Emperor. Havok, Phoenix (Rachel Summers), Polaris and what's left of the Starjammers, as well as former Empress Lilandra, stay in space to fight Vulcan. Vulcan eventually captures Havok and Polaris. That leads us to now. Vulcan is the second king
I don't know much of anything about the Annihilation end of things. All I know is that Annihulus destroyed a large chunk of the Kree and Skrulls Empires before being stopped in the first mini, and then the Phalanx and Ultron further messed up the Kree. Blastaar is said to be the third king, King of the Negative Zone.
In regards to R.I.P., finished...is a subjective term...
Batman R.I.P, in all technicality, finished last month. There has been zero resolution to it, though, and in order to properly understand it, you have to read large chunks of Morrison's Batman run, the current followup "Whatever Happened to the Caped Crusader" and the Final Crisis event. All told, I would just as soon skip it if I were you, it was pretty much entirely crap and not even worth a download.
For those who want to know:
Batman's driven insane by a new villain/villain group called the Black Glove, who claims to be his father, Thomas Wayne, referring to himself as Dr. Hurt. Dr. Hurt claims that the shooting was actually arranged, saying that Martha Wayne slept with Alfred in a drug addled orgy, so Thomas paid Joe Chill to kill her and make it look like a mugging, faking his own death. Batman gets hopped up on drugs and thinks he's the Batman of Zur-En-Arrh, another dimension or planet or some other bullshit. He also lives through what is essentially that idiotic cliche of 'i got advice from a kindly old man last night' 'but that kindly old man died last week OMGZ! Was it a ghost or a dream?!' The Black Glove society does some dance thing where rich people bet on whether or not Dr. Hurt can kill Batman. Dr. Hurt kidnaps Nightwing and hires the Joker. Nightwing is about to be lobotomized for about four issues while Joker sits and talks esoterically about nothing for three issues. Batman's girlfriend, whom he told his identity to for some reason that was never really clear, turns out to work for Dr. Hurt and suddenly is a bloodthirsty psycho out of nowhere. Alfred gets beaten up a lot. Joker kills a couple Black Glove members and Batman is drugged and put into a coffin to die. Batman gets out of the coffin and reveals he knew their plan all along and had, years ago, conditioned his mind to have a backup personality (Zur-En-Arrh) in case someone brainwashed him and drove him mad. He knew his girlfriend was a traitor all along too, which doesn't really account for him giving his identity away, but whatevs. He knocks out the power and Nightwing gets away. The Joker laughs and kills a couple more Black Glove people cause he wants to be a member. Batman chases Dr. Hurt to a helicopter and tells Dr. Hurt he's not Thomas Wayne, Dr. Hurt says he is, Batman says he isn't, the helicopter blows up. Batman is now missing for six months and presumed dead. He didn't die in the explosion and why he disappeared will be revealed in Final Crisis OMGZ. So basically, we have six issues of meandering, senseless and illogical bullshit followed by "Oh, by the way, this really doesn't matter, the actual climax happens in Final Crisis. GIVE US MORE MONEY OUR MARKET SHARE IS IN THE SHITTER!"
Yeah. It's pretty much garbage.