Death Inventory

Is there a way to do one of the following options. (Sorted by preference)

  1. When a player dies, remove all items from his inventory except one.
  2. Make certain items not movable from a death inventory (the opposite of specimen implants)
  3. When a player dies, make his inventory disappear/inaccessible, but make it possible to harvest him
  4. When a player dies, give the killer a certain item

Thanks for taking your time to answer.