The committee on applied superconducting apparatuses and characteristics of superconductors, the Institute of Electrical Engineers of japan (IEEJ) has made a data base on superconducting magnets which were built over last ten years in Japan. The outline of the data base is explained in the paper (Part I). In this paper (part II), stability and hot-spot temperature of a magnet are investigated. Minimum quench energies, minimum propagating zones, and Stekly's stability factors are calculated using the data base. Dependence of those stability parameters on the magnet scale is studied and the design trends of the stability are discussed. Hot-spot temperatures of the pool-cooled magnets at quench and energy dump process are also calculated based on the data base, and the recent trends of design rules for the quench protection are studied.