Wow, that's a lot of cards! I've only skimmed through them, but here's a few thoughts
A lot of these cards cause you to draw cards in your buy phase. That is often a lot weaker than drawing in the action phase, since you might draw some unplayable action cards. I suppose that's intended? But the cards don't really offer solutions in themselves.
The four-way split pile makes sense, since you're guaranteed to have the ability to play treasures in your action phase in the kingdom, but I see some power level issues. Track is really underwhelming compared to Mill, since it always reduces your hand-size. Maybe just slapping on +1 Card would make it more viable? This card could be done with only one dividing line, and should be done with the VP under the line, like this:
+1 Card
+1 Action
You may discard a victory or action card for +$1.
This turn, when you play a Treasure card, +1 Action
--
1VP
Also, for some reason it is missing the Grounds typing
I think you meant that Plow should reveal cards from the top of your deck, instead of from your hand? In that case it is pretty strong in the opening, it's better than Doctor at getting rid of your starting estates, as well as giving two actions. The fact that there are only four in the pile makes it tough for the last people in a 5 or 6 player game, as well as the ability to get bricked out if your opponent rotates the pile before you get any.
About Executive, I think it is really overpriced. Allies has a really similar card, Town, which costs $4, and might even be a bit stronger. Your card would be fine at $3, i think.
You have a few reactions here, all of which have some problems. When a reaction is triggered, nothing is really stopping you from revealing it any number of times, sometimes getting multiple effects. This makes it so that you can gain any number of coppers from Marsh, and drawing any number of cards from Mana or Ballista. At least Mana here should be rephrased like Horse Traders, which draws a card and makes sure to only do it once per Horse Traders you have.
The same thing applies to Scoundrel, letting you turn all non-victory cards your opponent buys into coppers. (There have been a lot of problems with the "when you would gain" phrasing, so I would recommend you to use the Exchange mechanic instead, like on the post-errata Trader) Also, it is unclear if you or the victim chooses which card they gain. There is another problem here: this is an attack that doesn't count as an Attack, which makes it impossible to block. The only other cards like that in the game i know of are Masquerade and Maelstrom, which usually don't hurt that much.
Then there's Ballista, a reaction that harms the attacker. This makes your opponents think extra about when they play their attacks, but there are some problems with having a reaction harm the attacker. I'd recommend reading the Fan Card Creation Guide:
https://forum.dominionstrategy.com/index.php?topic=699.0