Damage Reduction Mechanics

So, I have a fairly nice char focusing on Blocking and Defense--decent aoe dps to boot.

I've run in to a problem, however: I have 74% damage reduction and I can't find answers to what I should do from here.

Do I continue to use Fortify? http://pathofexile.gamepedia.com/Fortify_(support_gem)
Do I run Chaos Golem, also? http://pathofexile.gamepedia.com/Summon_Chaos_Golem

1) Will they stack with my damage reduction from my armor?
2) Will take allow me to pass the cap?
3) Will they stack with each other?


What have you guys found so far?

I got 86% dmg red with Rumis
Is fortify useless then?