So, I play Nutaku Aigis and I overheard that I should keep the spare Gold or higher rarity units for when Rainbow Crystals will be introduced and probably Second Awakening. That got me wondering about few things:

1) I heard that event units will cost less then units from summons. If that is correct, then does it concern all of the units I get on event, or only the one this event is about? For example, some events offer one or several Gold rarity units as a reward for completing loot on some missions. Will these units too have a decreased cost?
2) Recently I was unfortunate enough to roll Gold Mage Cyrus from my premium summons, who currently on Nutaku can be bought for 70 Demon Crystals on the Trading Post. That doesn't seem much in comparison to 5 SC, so I was wondering if units obtained from Trading Post too suffer the decrease in cost, and if yes, does it spread on units obtainable from TP that I rolled in Premium Summons?