Michael Corso asked:
When I go to iTunes to convert a file to mp3 (from AAC), the Advanced menu only allows me to convert 'to AAC'..it doesn't give me the option to convert to mp3. What's up with that?
The answer is that the option you get is the same as that set up in Advanced Preferences > Import. Change that to mp3 temporarily and iTunes will let you convert to mp3. In an ideal world selecting Convert would give you a choice of formats to convert to, but we have to make do with what Apple has provided us.
I've now solved my own problem (see following post) as to how to export a movie for transfer to a mobile phone. It seems that mobiles typically use AMR (adaptive multi-rate) audio format, and that is available with iMovie. Maximum rate is 12kbps, so not exactly hi-fi, but audio uses bytes fast! Similarly, for the file format you should choose 3GPP (Mobile MP4).