Just going to comment on the first few things that stood out to me.
Extortion [3] (Action)
+1 Action
Choose a Supply pile that is not empty, put 2 Coppers from the Copper pile on top of the chosen pile. Those Coppers has the same cost as the norm card of the chosen pile.
Firstly there are mechanics issues with this: you can't really keep track of how much the Copper is supposed to cost, because you're not meant to look through a Supply pile.
Secondly, this seems like it just sort of shuts down the game.
I mean there's slow and there's "I have to spend $16 on Coppers to get to the Provinces" slow.
Archway [5] (Action)
Discard any number of Victory or Curse cards; +$1 per each discarded card.
So, a less powerful version of Secret Chamber at more than twice the cost?
Quarry [6] (Action-Victory)
3 VP
+$3
You may trash this card, then gain a Gold, putting it on top of your deck.
There's already a card called Quarry.