Beregond is the name of the guard who took Pippin to the mess hall, it just came to me!
I'm woefully wrong on the first High Elf Sam met, though. That was annoying me, so I checked it, but I shan't give the right answer away...
It also occurs to me, however, that Glorfindel is the right answer to the wrong question - it is he who made the prediction of the fall of the Witch-King of Angmar.
Incidentally, what was the name under which Aragorn served in Gondor?