There's a theory regarding the world's total subconscious, known as the "collective unconscious". Some believe that accessing this can give you dreams of the future. The connection would be easier to make, as well, considering it all involved your friend/s. Perhaps on the surface level you were accessing HIS subconscious wishes. This may not apply to the car wreck.

Also consider that dreams and the waking life are like the chicken and the egg. We never really know which comes first. We carry our dreams with us as we go about our waking life, and our subconscious effects our waking decisions; but our waking life also determines what we dream about. It's like the sketch of two hands drawing each other
(that's by M C Escher, for the record).

I believe if we had more details about your dreams, you'd find that none of them were simply dreams of the future. Even the most simple dreams reveal some sort of dialogue between our subconscious and ourselves.