Here are a few last questions on interpreting the equations:
What will the rate of water flow be if permeability is zero?
When will the rate of water flow be the highest?
What happens if the osmolarity of the two solutions is the same (if they are iso-osmotic)?
None of these was really rocket science. The point is that the equation for rate of water flow is simply a formalisation of what our intuition tells us should happen. The equation puts intuition into mathematical language!