one of my first desperate jobs after moving to los angeles was driving stars home tour. imagine two hours in a poorly air conditioned van surrounded by the sort of people who think seeing julia robert's house is a good use of vacation time.
and about two weeks in i found a book that showed two thirds of the information i'd been trained to say was bull.
if you have specific questions i might be able to help. most of the mgm stuff you're describing is long gone. a few rko remnants are now part of the paramount lot. but other wise get this book and drive around on your own.
http://www.nrbooks.com/hollywoodtour.htm