She didn't shoot the gun perfectly, she tried firing it at a stormtrooper and left the safety on when she did so and she missed a couple of times before she shot the stormtrooper. The rest can be explained as The Force, though I feel like she may have flown a ship before due to her understanding of the Falcon, but I'm not sure when or under what context. Disregarding that, those with Force sensitivity can be great pilots, see Anakin and Luke, particularly Episode 1 Anakin (ugh). She could have learned of the Mind Trick while reading Kylo's mind or she might have been instructed at a very early age and just picked up on it again, remember, we have no idea who she is or where she came from.