Pretty Little Liars confusion?

I have been watching pretty little liars but i missed the 1st 5 episodes of season 1. I have been reading on the blogs that in the books Mona is A and Ally is the real killer of herself who is actually courtney.? Then I decided to go back and start watching episodes on my dvr and then I thought that hannah was just dreaming when she saw Ally in the hospital after she was hit with the car, but allison said to her " I was so afraid you were going to die I had to come back to see if you were ok no matter how dangerous it is" So is that the REAL allison or was it just a dream??? And what is the deal with Jenna why was she having Caleb spy on hanna???