3) You want to pull of Scrying Pool chains, and there's a better chance of it working if the Treasuries are shuffled in.
Is that correct? Playing 5 top-decked treasuries and then SP to pull up 6 other actions is just as good as playing SP to pull up 11 actions including the 5 treasuries, isn't it? Does having the treasuries shuffled in actually increase the odds of making a bigger chain (discounting what you would have had just from top decking)? My mathemability is failing me here.
I may be wrong, but I think yes it does.
Extreme example just to show the thought experiment: say you have 10 treasuries, 1 scrying pool, 15 golds in your deck.
If you stack 10 treasuries, then you'll get the 10 treasuries played, and have 5 golds in your hand. That makes $10+$15
If you don't stack the treasuries, have no treasuries in hand, then scry and draw 10 treasuries, you then end up with a 15 card hand that contains ten treasuries and 5 golds. You play the ten treasuries to draw 10 more golds, and that leaves you with $10+$45.
Obviously thats an extreme sample for the sake of demonstration, but I think its broadly true that scrying pool + drawing multiple cantrips = more cards in hand.
I guess for specific circumstances, you need to work out what chance the scrying pool is going to give you of a bigger hand, and balance that against the guaranteed but smaller payout of having treasuries on top of your deck. In the example above, it might not be such a good idea not to stack in practice, as the odds of both drawing that scrying pool and then drawing treasuries with it is going to be pretty low.
I think the more scrying pools you have, the less likely you'll want to stack the treasuries. Also, theres the question of how many buys you are likely to generate, how many $ you need to win, what other actions you have, etc etc.
Even so, I think there are definitely moments when its better to return treasuries to the deck rather than stack them where scrying pool is concerned.