Heart in Search of Power
2) Not all mobs drop the quest item but it appears to be 100% so with steady killing it takes around 2 hours to get 300 items. Here are a few of them. Keep in mind the splitting mobs like Blade of Splendor and Punishment of Splender drop the item for each mob too.
5) Back at the necromancer he asks you to choose your reward, I chose asofe this time which also gives a small amount of adena as well.