Well, I don't know what they are going to be doing with taking from other books. That would, IMO, take away from the spirit of that book wouldn't it?
Lewis wrote the books with specific thoughts and ideas in mind. You shouldn't throw more ideas in there or the audience will get lost and confused with the point of the story.
What keeps coming to my mind is in PC, the movie, they sort of take part from LB where Peter says to Edmund about what happens if you die over here?
It could be small simple stuff like that, and it may even compliment the spirit of the VDT.
Some people have posted some good ideas. I like the Caloremene idea, especially seeing that it's looking like they are really making the slave part of the story more significant or larger. I could be wrong. Just theories.
The unfathomable fate is something that still doesn't make sense. What could it be? Tash is an interesting idea, but I hope that's not it. Because I want Tash to be in LB and be something new, and surprising for eveyone. If we see him in VDT, and he's prevented or stopped from destroying Narnia, who's going to care if he comes back again?
Anyway, I'm not opposed to this adding from other books, mainly because I don't know what exactly they've done, I'm open to seeing what they'll do, but I still just wish they'd stick closer to the book as if it's good enough to stand on it's own.... WHICH IT IS!

- Twin

I really hope this movie turns out well because at the moment I'm not very optimistic. I've haven't been reading a ton of spoilers lately, but what I have heard is very different from the book If anyone has any information that I missed that could raise my hopes, that'd be awesome.

Well, I think the trailer will reveal a lot of answers to all our many baffled questions. Till then, we can only wait, really, till we get more official, solid information about the film.

- Twinimage

I really hope this movie turns out well because at the moment I'm not very optimistic. I've haven't been reading a ton of spoilers lately, but what I have heard is very different from the book If anyone has any information that I missed that could raise my hopes, that'd be awesome.

I'm not sure what information you have read but I think this post has a fairly accurate list of the information we have (at least no one has told me otherwise ). I think there is some hope in it. I find numbers 8 and 9 under "statements from people connected to the filming" encouraging.

If the LotGK is in VDT, it will ruin certain parts of the Silver Chair. For example, if she was in the movie, Eustace would know who she was, and how evil she is. Then, in the silver chair when they see her, he wouldn't take her advice to go to the house of harfang. He would realize, "That's the LotGK, there is no way I am listening to her! Those giants are probably not gentle!