Old Grey Gull

If I have Nagga's Ribs and Aeron Damphair with a duplicate, when I use Old Grey Gull to kill Aeron Damphair and I do not save it. How many Aeron Damphair's card can I return to my hand.

Just one, technically the copy you killed, not the one moved to the dead pile. —
"The Dornishman's Wife"

How this event works now? The Dornishman's Wife redesigns. If unique character has a all icons, i gain 2 gold and draw 2 cards and it gains 2 power?

Yes, although the power on the character only matters if you get to 15 (or can save the power via Shyra Errol), because the character then leaves play. —
Devoted Bloodrider

when two copies of Devoted Bloodrider are in play, does the ability stack? So every Devoted Bloodrider gives plus 1 ?

Yes, each Devoted Bloodrider gives +1 STR. —
The Prince that was Promised

Two questions: 1)May I have 3 different copies (of name) of Roberth Baratheon in my deck with this Agenda? 2)May I choose wich copies I marshall? For Exaple, Can I marshall Robert from Core when, before My other copy of Robert leaves play?

You may have different copies of the named character in your deck. You can marshal whatever version you want if you have different versions in hand. But if you have a unique character in play, cards with the same title can only enter play as duplicates. So in your example, your other Robert can only be marshaled as a duplicate to Core Robert. —
Marriage Pact

From www.cardgamedb.com

Question sent to Danny Schaefer:
Hello Daniel! A question about Marriage Pact: [text of Marriage Pact]. If I attach Marriage Pact to my own character (e.g. in order to protect it from Unexpected Delay), can I declare it as an attacker or defender?
Should I read "challenges against me" as any challenges in which I am the attacking or defending player? Or should I read "participate against me" as referring only to characters controlled by my opponents? I'd assume the latter, but Dany's text is very specific: [text of Daenerys Targaryen (Core)].
I'm not sure if this wording is just supposed to be extra clear, or if "participating in challenges against you" actually includes characters on both mine and my opponent's sides.
Danny Schaefer's reply:
Hello! The latter interpretation is correct. The character is prevented from participating “against” you in a challenge, but could still participate in a challenge in your side, as you are not taking part in the challenge “against” yourself. Daenerys’s card includes the “on an opponent’s side” text for added clarity. Thanks! Danny Schaefer