The Hunter quest, "Ancient Leaf" questline on Lordaeron

To whom it may concern,

I recently got the "Ancient Leaf" from Majordomo in Molten Core on Lordaeron server, and have been able to clear only 1 of the 3 related quests.

"Ancient Sinew Wrapped Lamina" - Completed

But the other two related quests, "A Proper String" and "Stave Of The Ancients" were not able to be completed.

"A Proper String" - Managed to defeat Artorius and Simone and retrieve their heads. But, Klinfran The Crazed didn't drop anything after defeating him, and Solenor The Slayer keeps blasting for 4k-5k damage which instant kills me.

"Stave Of The Ancients" - The Black Dragonkin in The Burning Steppers indicated they can drop the "Mature Black Dragon Sinew", but none have dropped so far. I understand that people say you have to defeat Onyxia to get it. Is this true?

Any information on this subject would be appreciated. Thank you.