The standard lapidary diamond wheels that have a 3/32 or 1/8 mandrel work very well. You can easily use any 100 to 400 grit wheel, most of the 600 grit plated wheels will not work well. There is not enough plating on that size grit to stand up the runout of most flex shafts, most micro motors will work with that fine a grit though. The nova points work very well for sanding the grinding burr scratches they and the the grinding wheels need to water to lubricate them.
An easy water setup is to use a small dish of water and a kitchen sponge. Put the sponge in the dish and fill the dish with water just below the top of the sponge. When the stone gets dry, wipe it on the sponge. You will be doing about as much wiping as grinding but it is easy and fast.
The rubber wheels that are use to smooth silver and gold work very well to further smooth the stone. These wheels are available in several shapes, with, and without mandrels. They are available in soft and hard rubber. Some people like one, some like the other, both work. They can be used dry but I would ware a mask using any wheel dry on stone.
Depending on how fine a finish you want, diamond compound on hard felt will give you as good a polish as you are willing to work for. There are several different diamond polishing products available for stone, it is mostly personal preference.
There are several books available on gem stone carving, you might want to read several of them for more ideas.