It is normal that when you loose hydraulic pressure, that the steering become hard or back to what I would call manual steering.
The noise & whine often is because air remain in the system and has to be bled out.
Is the pump still noisy after you fixed the leak? Can you tell us where exactly the leak was, did you replace the PS pump or..??

With no fluid to cavitate, THERE IS NO NOISE.....

Whoever told you it'* ok to run dry, or even low(so that it makes a noise), is wrong....