If I discard my hand to the reserve limit and discard a unique character......to the dead pile or discard pile do they go? Does this mean if I have a copy I have in my hand is usless?

same question with randomly discard from intrigue challenge and if say....I get pillaged so I discard from the top of the deck and is Jon snow or yoren or stannis? (a unique character)

You answered your own question:

"If I discard my hand..."

"...randomly discard from intrigue..."

"... discard from the top of the deck..."

They all go to the discard pile (not the dead pile). This has no impact on the other copies that remain in your hand.

Thank god....Greyjoy pillaging would be OP If they sent unique cards to the dead pile. Thanks!

For now, the only effect that can send a card to the dead pile from out-of-play is Heads on Spikes.