Quote:
*  keep the intro music and and all other music that is not associated with the vocals 
*  remove those bits of the song which contain the vocals 
*  replace the cut sections with light instruments that would normally accompany the vocals. 
Have you considered creating a midi file? If you use the YamahaXG 
(NOT Roland) standard, you can get a very good sounding song. What you are attempting sounds wayyyyyyyy to much work, and quite frankly, without the right audio editing software (something that can specifically cut/paste at a 
zero db X-point) your result will sound horrible.