Do dreams really predict your future?
no, but they can provide insight into your subconscious, letting you know about fears and desires you did not really think about, they are not magic, but they can be used in fields of science, such as neurology and psychology.
They could give you inspiration to do fun things. Last night, I rode a bus from Pennsylvania to London, England. Then I walked to Pickadilly Circus and played guitar with David Gilmour.
No, I don't believe so.
Nope, they're just a safety valve for your brain