Hi Chris,
  The CC sampling licences may also be appropriate --
see
   
http://creativecommons.org/license/sampling?format=audio 
I don't think they would be right for Ron, as they permit 'creative
transformation'. They also have a restriction on use in advertising,
which is pretty vague. I guess that's because TV adverts can make
more money for artists than their records do...
  Am I right in thinking AGNULA doesn't include any
non-free stuff by
 default?  
Yes, although you can add a 'non-free' apt-get source.
Cheers
Daniel