I have been developing commercial operating systems almost 15 years. Not only do I deal with this subject matter on an almost daily basis, I can offer a unique and practical viewpoint.
Incidentally, I still have my "Dinosaur" textbook (Operating System Concepts, 4th edition by Silberschatz and Galvin). It may not be latest edition, but to be honest, for the questions you posted, very little has changed.
Hope to hear from you.