damb!
i think you can test the regulator off the bike with a mutlimeter, i think you test the resistance between the prongs. My vfr400 book had the readings you should get and i checked it regulary as they were a common problem.
If your regulators gone it will overcharge the battery as its not regulating the stators output, for the stator to crap itself id say the regulators not doing its job and the stators burning out??
Is your old battery flat? or did it drop a cell?