Mage/Dark Wizard Recommended Powders for Armor

Currently using this build by seresdia.
https://hppeng-wynn.github.io/builder#7_07R0U20JL0FP0050050K40UN0CD0U0t0o1V0e1g00000zz++++-tMpxfswB
WynnBuilder build:
> Cancer֎
> Ornate Shadow Garb
> Greaves of the Veneer
> Ensa's Ideals
> Summa
> Summa
> Prowess
> Royal Stormy Amulet
> The Nothing []

Here are some questions I have regarding powders on armor:
What powders should I use for the armor? (A precise allocation of what powder on what armor would be appreciated)
What is the maximum number of a single type of powder should I be applying to my armor to get the passive? (I heard that apply all the same powders to all armors is not beneficial since you get the full benefit of a powder passive at a certain number of powders)
Do different elemental passives stack? For example, would Kill Streak and Endurance stack?

Thanks!

 

Seeing as you don't have - elemental defence, powders aren't really gonna do much for you.

 

powder specials do stack, but they are not going to be increasing your dmg in that build