Sorry about the belated response, burgs. I haven't checked this part of the KW forum for a few months. You're probably just the same as me, but even so I may PM you indignantly in about April/May (of 2013). You have been forewarned.
Yes, Arvedui was the last king of Arnor.
I thought the seer involved ("Not by the hand of Man shall he fall") was Malbeth. But I could very well be wrong. I'm also pretty sure that a future King of Gondor (before Aragorn) was there at the time as a youthful prince.
Anybody care to name the young twat?