On slowing yourself down -- yes, you do slow yourself down more. Again, the hand-size attack hurts you more than your opponents. They would get cut down to 4, but you get cut down to 3 (Confusion taking up a spot in your next hand, plus the card you would have to topdeck from playing Confusion). And if you don't play Confusion, it still slowed you down (being in that hand) and will continue to slow you down after ONE reshuffle (being in a future hand). The Ruins just means it will hurt some more in the shuffle after that.
no, you don't. the top deck on buy is optional, you can just gain it on your discard pile, then your next hand is unaffected and you still get the coin token.
and it's after 2 reshuffles, because after the first reshuffle, the ruin is in your discard pile. you need to reshuffle again to get it into your drawing pile
If you decline to top-deck, the Confusion is still in your discard. After one shuffle, the Confusion itself goes into your deck. That Confusion is junk that effectively Minion/Militias the hand it comes up in, so it slows you down. The Ruins that comes after is just icing.
alright, so it hurts after one reshuffle, not two. but it still hurts
after one reshuffle, not in your next turn.
you could tweak it so confusion itself goes onto your discard pile too after you shuffle it into your deck... which in consequence would mean that you never shuffle it into your deck, which means you also can't leave it on your discard pile. that would be pretty confusing.