Hello. Your water flowing noise is interesting. I once had a golf, bought new. It had a ticking noise from the wind screen area just about 40. The car went back to the dealers many times. They changed the wiper blades, the windscreen trim. They tried lots of stuff but it proved to be a stubborn problem.
It was eventually traced to a sycamore seed trapped below the wipers in a void (where the wiper motor sits). The sycamore seed for those who don't know, is the seed shaped like a blade that rotates like a helicopter when thrown in the air. It would appear that when the car reached 40, the airflow would be enough to make the blade 'take off and fly' thus creating the ticking noise as it collided with the body work within the void when rotating.
Just a thought.