Scott,
To answer your question about the 12-string guitar.
The normal guitar is tuned in 5th's, ie from E string at the 5th fret to A string open is a fifth.
Having said that, above the G string, it reverts to 4ths for the B and E strings.
Where is Electure when you need him?. [Linked Image]
An E string on a 12-string (the second string in the group) is an octave above the parent (lower) string.
An octave can be thought of as this, the first two notes of "Here Comes the Bride" are one octave apart.
They are eight notes apart, in the key of C.
I'm of the opinion, less strings, less confusion!.
Hope this helps mate. [Linked Image]