CONFUSED ABOUT HOW MUCH FALL TO WASTE IS REQUIRED

[Briney]

I am hoping someone may be able to help with the answer to a couple of questions. I have looked through past forum letters but couldn't find the answer as yet.
1) what is the fall to waste ratio for a bathroom floor/ laundry floor.
2) what is the fall to waste ratio within the shower area (tiled floor)
3) What do tilers use as a screed mix ie sand:cement:lime:bonding agent.
4) One tiler i spoke to told me to waterproof before i put the screed down where as another told me to paint the floor with a bonding agent then spriNkle cement on top and then add the screed followed by the waterproof membrane i am now slightly confused.