Across the Universe, anyone see it?

okay, i am a huge beatles fan ( just the music, never did any research on the band really, so i don't know much about them ) and totally loved the movie. i just need some help understanding something. what is the signifigance of the girls Sadie & Prudence?? and also, was the man they called JoeJoe supposed to be Jimi Hendrix? this was very confusing to me?