1) I am perhaps less inclined then some to say one's path was
pre-destined. Fate has a role in Middle-Earth obviously. In terms
of lineage, Aragorn is no more or less "royal" than Arvedui, or Earnur or
Ar-Pharazon or many others. What is key here is his upbringing, his vast
experience, and his force of personality. These combine to enable him to take
the Paths of the Dead at this key moment and regain the Kingship.
2) Desperate confidence? That seems to describe Aragorn here...he's
desperate, but confident in himself now and his
decisions.