It shouldnt be black 1st off bud, and I have never heard that about damaging pump how do you think when car goes in for service they replace it.
What do you mean fluid is coming out of cap? It usually whines when fluid is low or blocked?air in system. First start car remove cap and slowly turn steering from lock to lock do this about 10 times (will bleed system) however if its black I would change fluid as something is wrong.

WES