Dragonwrath Delegation quest guide and tips

I just finished the first gathering quest for the Legendary staff. I cleared both Normal and HC this week to get the final Eternal Ember, and I am now on this quest.
I have several questions :

  1. If I reset the raids, can I still do the bosses for the quest items that drop during their fight, from the first four bosses?

  2. Since I’m level 80, will I need to remove all gear so I don’t one-shot the bosses?

  3. Since I’m a Mage, can I do the mechanics solo or will I need another player?

Any other tips or suggestions for specific bosses are welcome