I want to compress audio tracks to MP3s, what do I need besides from EAC?

Remember that EAC does not supply a MP3 codec; you may use the LAME, Gogo or the BladeEnc DLL’s (or FAAC Dll for AAC compression) by copying them into the same directory where you copied EAC. Then you will be able to choose the installed DLLs in the compression option dialog box. Of course the quality of MP3 is based on the encoder and the bitrate you use. Beside the DLLs you could also specify external command line compressors that will be executed after an entire track was read (and not on-the-fly).