@Jeckyl

Definitely get the i170 weapon. It will be fine until you get the Hive drop.
Only use Ifrit for Bismark. It's not worth it just to Contagion your dots on the dragons and since pets dont get the debuff you can just leave it on whatever one.
(Also I dont think Garuda can hurt the carapace from a distance.)

Sounds like you have the rest down pretty good.