Wouldn’t the water from the well be able to bring back Belle’s memories since it has the power to return that which is lost?
As for the Rumple/Cora kiss, perhaps it is sealing their truce, similar to how a handshake can be seen as sealing a deal? Also, Rumple is the most powerful man in Storybrooke, Cora may want to ensure he is kept on her side.
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All magic comes with a price!
Keeper of Felix