Discarding cards while using Race/Class abilities

[sanya2ya]

While using abilities of class cards like Cleric that don't specific about "in your hand" cards that must be discarded for using this ability, can player discard that Cleric card itself for gaining bonus, or that discarded card wouldn't count cause of losing ability due discarding card? And can be discarded other active Race/Class/Supermunchkin/Half-Breed? And if Class/Race have Modifier card on it like Elder or Dark, can it be discarded for using ability too, but not discarding Race/Class card? And can be discarded item modifiers cards like Cheat! or for Example "...of Doom" (from Unnatural Axe) for ability but not discarding Item which Item modifier is belongs on that moment?