The reason the other side is left unfinished is to show the "skin". This is the sign of a high quality stone.

I have 2 stones from 330mate and 1 from O_S. only 1 of the 3 have been lapped. I have had the writing fade on the other 2 I haven't lapped. So, if you feel it is needed, lap away.

For use, just spray a minimal amount of water on the surface. These get finer with use. I am trying to enhance that process on one of my stones by rubbing the surface just a little bit with a DMT plate and then taking an eBay junker and doing a lot of passes each session. I think I have noticed it becoming finer.

I think I read somewhere that the surface of these is somewhat porous and that the slurry accumulates in the pores rising out when water is used to help with the polishing process. It's the slurry particles that get smaller with use.

Of course I could be remembering wrong. I am sure they get finer with use.

I did have a crack in one of them that seems to have filled in somewhat and I no longer feel it when the edge passes over.