I actually dont own a 12 string, but I can tell you playing is playing, if you practice 8 hours a day on a lute youll still get better at electric guitar simply because your working those muscles and relatively the same brain areas. now as for songs I know that the intro to stairway is on a 12 string and Hendrix did a 12 string version if hear my train a' comin, though Im sure most acoustic songs could be adapted. anyway best of luck and happy playing!