- Well, Frederik, how about this: although we know Elves have a variety of special powers I think this comment is metaphorical rather than actual. I choose to belive it's his emotional reaction to the sadness of the ruins all around him - the ruins of a once-great culture, his fallen kindred, that Legolas is just beginning to get to know and understand (being a wood-elf his whole life)

...Gimli when in Dimril Dale, where because of Frodo's fears (they lag behind) he listens to the earth, and says he does not hear anything but the plants and stones' "nightspeech". Strange abilities, is not it ?

To me this does not show a "strange ability". Frodo is afraid because the Orcs are after them. Gimli listens and hears only the ordinary sounds of the woods. If an army of Orcs were nearby I presume Gimli would hear the vibrations through the ground. But he doesn't. I've been outside in a forest at night, sitting alone and listening. I know what Gimli (Tolkien) means by "nightspeech". You should try it. You may still call it a strange ability because it is so rare in our modern world to stop and listen to our natural world, whether it's day or night.

: Oh, and yet another thing that puzzles me. No two things !
: - Frodo is stated to be the one that sees best in the Mines after Gandalf, because of his Morgul wound and presumably of his bearing the Ring...

I'm at a loss, here. I would guess mostly because of the Ring.

...but what about Legolas and Gimli ????

Gimli feels the most at home but I don't know that he can actually see any better. He's never been here but as he says "all Dwarves dream of Moria". Legolas should be able to see very well in the dark but maybe because he still thinks of Dwarves as the enemy, being in their former stronghold may cloud his vision?

...Related to that, how come Haldir in Lorien needs the light of a lamp to study Frodo and Sam's faces in the flet ????

Don't think I can help here. Anybody else?

: - Another unpleasant detail : the Balrog issues a "terrible cry" as he falls from the bridge... quite unconsistant with the Letters and Tokien's complaints about some adaptation having made the Balrog laugh (if my remembering is correct), whereas he considers him as... mute ? Or was it just that the Balrog remained silent ?