Reshaping stones on flex shaft?

I would like to reshape some stones on my flex shaft. I read some
other posts on this recently, and most of it makes sense to me. I
don’t have any idea though what would be the best cutting or sanding
tool to do this with, or if you need to keep it wet. I have avoided
getting into lapidary work, but now I feel like maybe I am ready to
take on a little of it. I would probably just start with reshaping
some stones I have. Also I would like to know how to repolish amber
without burning it. I am clueless about how to grind down and
polish stones so any tips to get me started would be of great help.
I do have a grinding wheel from the hardware store and also a
stained glass grinder that uses a wet diamond wheel I thought might
work. I would like not to buy a ton of equipment, ideally I’d like
to use or fix up what I have to make it work. Any tips would be
great. Also a recommendation on a book that is pretty easy to
follow on cutting cabs from roughs would be great.