Slurry stone, Nagurra Stone?

I would like to get a good slurry stone, but I'm confused between slurry stone and Nagura stone. I'm new to the honing scene but want to start out right. My Norton set has a prep stone? Can this be used on a coticule or a chinese 12k. Or do I have to get a stone for each type of medium I'm using? Is there a good overall slurry stone to use on everything? I just don't want to botch things up when I do start honing my razors. I would like to move into restoring razors and blades also and being in my condition I have alot of time to do this so I want to do it right. I also know that I need to take my time and learn step by step. So any help is appreciated!

The Norton Prep stone should be called, and used, as just that.... It is great for cleaning off swarf from the stones, during honing, but I would not use it for actually slurry, on anything over 1k and even that is questionable...
I use mine on every stone as a quick cleaner, and then rinse, and go back to honing... and that probably is more out of habit then real necessity...

Nagura is a specific layer of stone,as in the nagura used by nihonto polishers, but has become a term synonymous with slurry stone.

Sorry I don't know what the prep stone is.

A diamond plate makes the best I think, but sometimes it's fun to play. I've used a soft wa****a on bbw, seems to produce only purple. Sometimes i use my coticule on asagi, but for pure reliability i trust 1200 diamond plate.

I use a DMT diamond plate to work up slurry if I need it quick. I figure the slurry it produces it the same grit as the stone it produced it from, of course. What more could one ask?