Not sure about the loop question.
As to the wool, that stuff can irritate your skin; you may want to be sure to have gloves, a mask and goggles to protect yourself. (What's the difference between vermiculite and rock wool? I believe that vermiculite has asbestos in it?) This thread
has some photos of old parts...
Check the library for these books which probably answer your questions (I know that the first one has a lot of history in it):Old Electrical Wiring Maintenance and Retrofit
by David E. Shapiro (out of print)Your Old Wiring
by David E. Shapiro
[This message has been edited by ThinkGood (edited 02-21-2003).]