They are basically trying to re-start the franchise, much like we have seen done with Nolan's new batman movies. As such, they are re-establishing familiar characters as if they were new. It would help to know a little about the original characters (knowing who Spock is wouldn't hurt), but it isn't essential and you definitely don't need to know all the minutiae of the franchise to follow any of it. Folks who do know the old series really well will get a few chuckles from certain references...