Luke Skywalker from the end of The Force Awakens and Luke Skywalker, the protagonist of Episodes IV V and VI, are the same person.
A Lightsaber’s blade is made of light, and is shaped like a saber.
Kylo Ren has actually been the true villain of the movie the whole time. In the scenes where he tortures people for information, blows up planets, and tries to kill the heroes with his lightsaber, he was secretly trying to hurt them.
This might not be the first time Han and Leia have met. The way they look, talk and hug each other, and the fact they have a son together, suggests that.