what is "the next time in this round" in Ascension?
When you buy the card in Example 1, you don't get 2 runes. Why would you think that "The next time you..." is applied?

All of these things happen when you play the cards, not when you buy them.

Many times, the order in which you play cards from your hand does not matter. Bt if you are planning to buy two cards in a turn after playing the card from Example 1, make sure the one that you buy first is the one that you want to go on top of your deck.