Trying to cover many posts in one as per our Esteemed Leaders request.
David, the box of salt and seasonings doesnt' replace the earth and Mallorn seed, it's in the books that Samwise, along with his pans and cooking gear has salt. It's a detail, not a substitution.
I've been reading over at www.theonering.net
for over a year. They cover articles and information from all over relating to both the books and the movies. And there's more info in the commentary tracks on the extended versions. Movies work differently then books, re pacing, climax and so forth. That guided why there is not Scouring of the Shire. On the other hand, I read articles this week that there are something like 20 minutes of endings for all the major characters.
The Faramir change is talked about by Philippa Boynes and Fran Walsh. For the movie, for everyone else, Elvish, Istari and human to be tempted by the ring and then have Faramir totally unaffected took the ring's power and gutted it. The relations between Faramir, Boromir and Denethor are right from the book (both main story and appendices).
Minas Morgul is shown more in the RotK as is Shelob.
Well, Sauron doesn't know much about Hobbits and doesn't know which one has the Ring, so it follows (per movie story line) that a small person sensed in Osgiliath and then via 'palantir' could be the same one for all he knows.
From all I've read, the Grey Havens are done well indeed. ymmv, but we'll know soon.
That's probably enough geeking for now, don't want to weary anyone.
If you go here: http://www.wgbh.org/wgbh/pages/pri/spirit/listen.html
and have RealPlayer, you can listen to the "Sound and Spirit" program about LotR, with varous musics, and some discussion.