As far as cleaning,I would use only a mild soap and warm(NOT hot) water. A soft toothbrush will help clean the "checkering" etc. I don't really know how the "bakelite" or gutta percha would "react to anything "stronger".
I have always felt that the frequent broken corners are caused as much by a prior owner "overtightening the grip screw". Notice that most of the breaks are by the locating pin. Of course,some were "dropped"!