Good luck. I wouldn't use anything on the 1000/3000 (from the picture, I'm pretty sure it's a straight trad. Suehiro, even though it's marked as "Cerax"). The additional stone with the synth is not for raising a slurry; it is just for removing swarf/glazing, so as not to need to flatten so much with a diamond plate or sandpaper on glass. For lapping, yeah, either a coarse DMT or ~P320 wet/dry sandpaper with water on a thick sheet of glass.