Actually,
Heavenly Creatures is anything but a blood 'n gore film. It is a sensitive study of the disturbing friendship between two teenage girls with an intense fantasy life, and the tragedy which ensues when their parents try to separate them. It is based upon a true story. Not much blood and gore in sight, as far as I recall.
On the other hand, you missed out
Braindead, which is one of the goriest films that I have ever seen, although very low budget and wonderfully tongue-in-cheek. Well worth a watch, if you can stand the gore.
Again, I don't really that think that Saruman shooting a fireball down from Orthanc is something to get overly concerned about. The films are already replete with spectacular special effects such as this, designed to thrill audiences (something which they have been incredibly effective in achieving). Non-book audiences will expect a cornered wizard to hurl the odd fireball, and Jackson has to cater for them too. These are not just "our" films.
Also, I had read that it was with much reluctance that Jackson omitted this scene from the cinema release, in view of the wonderful way in which Christopher Lee delivered his dialogue. So I have high hopes that the "Voice of Saruman" will be present. It's hardly surprising that they included a spectacular moment in the trailer.
But (and I'm sure that I'm beginning to sound like a stuck record with this line) I really think that it's worth bearing in mind that these films are not meant to represent a facsimile of the book, but an adaptation of the book on screen. The intended audience is wider, the story told is different, the characters are different (in some cases, quite significantly) and the themes that the film-makers have chosen to emphasise are different.
I do think that it's best to sit back and enjoy them for what they are: well-made blockbuster films based on the book by Tolkien. Then go back and read the book.
