Did they remove cR from Halo 4? And will there be large amount of different armor and armor pieces in the game? Or will it be as simple as it was in Halo 3?
Yes. Now we have something called SP (Spartan Points). Which will be used to customize loadouts.
There are a large amout of armors. Some will be unlocked through Commendations, others through Achievements and so on 
There’s still a currency system, but now it is used to buy items to customize your Infinity Loadout. Most armor, it seems, will be unlocked through completing achievements, reaching a certain rank, or by performance of some other special task.
TBH, i think SP will make it easier since getting cRs in Reach was dragging.