Not sure about the East West Libraries. I imagine you can manually move them to an external drive and then create aliases of the folders and place them in the original location?
For Apple Loops, simply drag them from the Library/Audio/Apple Loops folder to your external drive.
Delete the originals from your system drive.
Now open Logic and drag the folders of APple loops from your external drive onto the Loop Browser in Logic. This will re-index them.
Good question. Try the 'Apple Loops' folder. If for some reason that doesn't work simply select and drag the individual 'Apple loops for Garageband', 'Apple loops for soundtrack pro', iLife sound effects', etc on to the Loop Browser.