[Rurik]

Originally Posted by Dark`

Spoiler for 3):

The other thing is that Ryuk also mentions how if a Shinigami kills someone at 40 years of age when they were supposed to live until 60, those 20 years of human world time get added to the lifespan of the Shinigami. So it does indeed seem like it is simply a difference in calculating the time rather than it flowing differently.

Spoiler:

The eyes gift also expand the Shinimgamis Lifespam