Saw it on Saturday night - loved it!
Ok first and foremost and as has been mentioned 50 times already there are holes that the audience has been asked to fill, which is convenient, because Rey is smoking hot. back to the movie plot now
I tend to feel that Rey is a Kenobi lineage - could be Skywalker but not certain at all. My "out there" prediction is that Poe is her brother.
Having only seen the movie once I seem to recall that when discussing why Luke bailed, was it mentioned that the unnamed student, presumably Ren, killed the other students in training?
Just that one of his pupils turned and ended it all. We later see, during Rey's lightsaber induced visions, Kylo Ren and the Knights of Ren after having slaughtered the Jedi trainees.