#3
just play any song with chords. it'll make it sound better.

if you want some song recomendations, try :

hotel california- the eagles
wish you were here- pink floyd
time of your life- green day

aslo, nothing else matters by metallica sounds amazing on a 12 string
#5
Wish You Were Here by Pink Floyd
Stairway to Heaven by Led Zeppelin (of course!)
Knockin' On Heaven's Door by Guns N' Roses
Fade to Black by Metallica

those are my favorites to play on my friends 12-string
"Would you tell Picasso to sell his guitars?" - Jack Black

Quote by Lt. Shinysides

my dick is generally better than yours, and is more pleasing to look at and hold.
your dick understands and accepts this, and is willing to just move on.
#7
Try searching, theres been lots of threads asking this question. While im here though, my favourites are:

Dream Theater - The Silent Man
Zakk Wylde - Throwin it All Away

Check out John Butler also, he pretty much exclusively uses an 11 string guitar (a 12 string with the octave G string removed).