What tools are there to convert flac to mp3?
I recommend XLD, which can convert directly to and from a variety of audio formats, including FLAC, MP3, AAC, and Apple Lossless. It's available both as a command line tool and a regular GUI app. And best of all, it's free!
There are links here for downloads. These will not convert to .mp3. However, you can convert the flac files to wav, and then using iTunes (or something else, but you are on a mac..) you can then convert the wav files to mp3.