Curse die rolls by dead taoists
Well, the situation of dying with an unresolved Curse die isn't addressed specifically in the rulebook, but your second question is!

From page 7 in the rulebook, under "Death of a Taoist"


  His board becomes possessed (see neutral board below) and the ghosts occupying 
  it continue to act, despite the Taoist’s death. The steps 1 &amp; 2 of the Yin phase must 
  be played. The other players will have to suffer the effects and consequences of 
  the ghosts on this board.


From page 10 in the rulebook, under "Possessed Board"


  A neutral board that has lost all Qi tokens 
  is called "a possessed board", Its specific 
  power cannot be used anymore through 
  neutral power tokens. 
  Any further loss of Qi points (i.e. board 
  overrun or tormentor) must be endured by a player of your choice (the green 
  Taoist’s power is ineffective if Qi loss is due to the curse die).


So if a player is dead and a curse die roll triggered by a ghost on the dead player's board causes a loss of 1 Qi, somebody else has to lose the Qi. Whether that somebody else must be decided before or after the roll is made is unclear. I would apply this ruling to the situation you present in your first question as well, the game doesn't want someone to weasel out of a curse die roll!