Nickname - as far as getting listed on DMOZ - it really depends on how you design the site - if it's all just affiliate ads and that is the main purpose of the site(which is what it sounds like if you want a domain with MP3 in it) then its gonna be real tough to get in the directory
On the other hand, if you do a site that gives some value to the surfers and the advertising is secondary - then its definitely worth a shot
Not answering for the sponsor here - but I doubt that they have a patent or copywrite on the term MP3 (actually Im thinking about patenting the technology of playing songs into the human ear) so you should be fine with any domain that has the terms
