Finally picked up this expansion, and it looks amazing. I have a question regarding the 6 new Improved "X" cards (X being Trade, Research, Warfare, Production, Colonize and Survey). These new versions have different costs and symbols than their counterparts in the base game set. Are the new versions meant to be included in the Technology card piles along with the old versions (so there will be 5 of each kind of Improved "X" card), or do they replace the originals? Thanks.
They do not replace anything. Add them to their respective stacks.
If you look closely, you may notice that Improved Warfare (for example) used to only exist in the Fertile and Advanced stacks. The new Improved Warfare card is in the Metallic stack.