A green hide is one removed from the carcass, no salt or other preserving chemicals. Can be scraped of fat and connective tissue or not...
http://www.braintan.com/ Go to the "Hide Out Discussion fourm". They have a section on rawhide..
There are many ways to remove the hair:
bucking - soaking in an alkaline solution.
dry scraping - stretching on a frame and physically removing with a sharp tool.
sweating - basically let bacteria and nature loosen the hair for you.
there are others as well..