Flowing water?

[Daemian]

For the stairs, I would use a particle system. Several copies, one for each step.
You're gonna have to learn how to use the ParticleEditor (if you don't).

You place the first PS, make a copy, move it to the next step on the stairs, then make a compound out of the two. Then start making copies of that compound to complete the whole staircase.

After that, if you have more stairs to fill up, you should select all those PS you just put, and make one single compound out of them.

Then you can make copies of that compound to fill the others stairs.
For the corridor you should stick with water planes.

And for the step sounds, you place liquid areas everywhere you have water.
There are also some water_streaming sounds you can use in /sounds/16/