Yeah, Argeleb was one of a long line of Ar-s in Arthedain, but I couldn't have told you which.
Now, for your password... I like the look of these clues. One that jumps out at me is #9, which sounds like a name of the form ELE????NE. A logical guess would be
ELESTIRNE, who I know you've been thinking around; I can't make 'stir' the beginning or acronym of anything, but I'm happy to assume it could be.
#7... Shakespeare had many kings, but the one that leaps to mind (and I think the only one who's 'King' in the title of his play) is LEAR. I'm seeing the clue as indicating an anagram of his name around a direction...
ELMAR the Numenorean is a possible, though M-as-direction is a stretch (Middle?).
hS