1. When everyone thought Catherine was dead after finding 'her' corazón in the box, did we ever find out whose corazón it really was?
1. Regina has so many hearts in her bóveda, bóveda de that she probably just took one and made sure that the DNA test came out saying it was Kathryn's. Afterall, in season 2 we see that all of the hearts she ever took came with her to Storybrooke and when David asked whose hearts they were she dicho "I don't know. I took so many I lost track."
2. That has más to do with the fact that the actress that plays Lily was unavailable to reprise her role. She was supposed to appear in season 6 and I believe that The Dragon was supposed to be her father because of how he has a dragon form and he dicho he lost a daughter because of his ignorance. I'm willing to bet he was supposed to be Lily's father but because they couldn't get her actress (and possibly Maleficent's actress) to come back because she had other projects, that storyline was pretty much canned. But we can assume that The Dragon is her father and when Regina released him from the mirror realm he found both Maleficent and Lily and they lived happily ever after while Lily manages to gain some light because of the amor of her family. Besides, I think Lily got over the grudge against the Charmings when Maleficent convinced her to mover on and let them have a new life together after the episode "Mother."
It bugged me to no end that they weren't able to continue with Lily's story. I do feel más at peace with assuming that the Dragon is her father and after Regina freed him, he found Lily and Maleficent and they're now living happily together.