RE: the 6 picture deal / 9 picture deal stuff, I'm pretty sure that they work that into the contract so that the studio can have the actor if they decide to make those movies, but they're not committing to make those movies. I heard it reported that Cobie Smulders (the actress who plays Maria Hill) also got a 9 picture deal, but once again, that doesn't oblige Marvel to make 9 movies with her, it just means they can ask her to be in up to 9 movies and she is obliged to move her schedule around within reason to accommodate them.
That's pretty much how it works. You make an x picture deal with actor y, they're obliged to be in x number of pictures for you. Doesn't matter what they are, or if they're any good, they have to do them even if they have better offers on the table. This is why Halle Berry actually turned up to accept the Razzie for Worst Actress in Catwoman. She thought the script was dumb, she didn't want to do it, but she was under an x number of movies deal with the studio so she had to.