Well in the book you don't actually see them fight once they come the fight basically ends the men win.
But the army of the undead was very strong, i remember a quote i read, that said something like only their presence made their enemies frightened and they couldn't fight.
Violette i think that point with Sam the movie made it better than the film. Since indeed it was far more dramatic for Frodo to sent Sam away and then Sam come back and rescue him.
Alright to us that read the book we don't like it being changed but it is inevitable.
Eowyn did kill the witch-king, and Theoden did see her, he recognised her in the book
"Eowyn, Eowyn! he cried at last, Eowyn how come you here? What madness or devirly is this? Death death death take us all."
he didn't know she killed the witch king though. Marriage of Eomer and Eowyn, Saruman simply not enough time. The film was 3.20 long. A lot of people though it was too long. Imagine if those things were in too... Saruman will be in the extended edition dvd btw i don't know about the marriage, don't think so really, not that important to be in the film.
Legolas killing the oliphaunt, wasn't anything in the book
The eagles coming suddenly, it's the same in the book. Did they destroy the nazgul in the movie, i think they didn't maybe one or two. The nazgul (or most of them) fled to mount doom once they felt the ring since Frodo wore it, both in the movie and the book if i'm not mistaken.
Anywa the point i'm making is that it is impossible, more than impossible really if there is a word to do the movie like the book. No way not even close. The amount of facts in the book is tremendous unbelievable really.
If you want to learn about it read the book.
Jackson made a movie, the movie needs action drama tragedy agony not blah blah. Otherwise even the fans of the tolkien would get bored of it.
That's it...