I feel like Fin will end up learning the force as well, maybe not as strong as the girl, but still learning it. Remember when Kylo Ren was about to board his ship in the beginning after the attack, but stopped dead in his tracks to look at Fin? I feel like he sensed the force in him, since Fin was able to make the distinction that killing all the villagers was wrong and stand up to them by escaping, I definitely feel like he'll have to ability to learn the force, they're just building up to it you know? Like, why show us everything awesome in the first of the new movies? It'll just be even cooler when he learns it later on. As for the Rae(Ray?) being so proficient in the force though not trained, you have to take into account that her father is presumably Luke Skywalker, the one who restored balance to the force. (I REALLY believe he is her father since his lightsaber has been passed from generation to generation and then called to her). It was like a do or die kinda deal, it didn't work the first few times. As for her being able to keep Kylo out of her mind, the way I took the character is that he's not a Sith Lord(yet) he didn't come off as anything more than a child to me. Someone who knows about the dark side, and wants the power, but has to many issues and lack of discipline to be a truly powerful Sith yet, so her natural talent in the force comes from the strong lineage she has in it. Just my opinions, I loved the movie and can't wait for the next one.