The development board is supported by Spectrum Digital Incorporated. You can find all the documentation at the eZdsp5535 Support website. There you will find manuals, errata, schematics in pdf and orcad, gerbers, and layout info. You can also download software and information for booting over SPI (the board will also boot over SD card). An audio expansion board is listed, but only schematics and hardware information is provided at the time of writing.
According to the press release from TI, the included code composer studio is a full-featured version normally priced at $495. I expect the software tools will be limited to this processor family, but that would still be a good value.