What I want to know is, will D/D/D Oracle King d'Arc's effect work on cards like Exchange of Spirit and The Winged Dragon of Ra's second effect as they state you must "pay" life points not "take damage".
The answer is no. Paying lifepoints and taking damage are two different things, just like an effect that sends a monster to the graveyard is different from an effect that destroys a monster. The wording is important. Because the word that the card text uses usually matters, paying lifepoints for any reason will not equate to taking damage for cards like D'Arc. You can read more about taking damage vs. paying lifepoints here.
Any cards that specifically inflicts damage to yourself will work, however. Blazing Mirror Force and Ring of Destruction both fit the bill, while also offering useful destruction effects. If you want a full list of cards that do this, you can find it here.