To download all the CAD files needed to build and run the RepArm, you can visit the RepArm Github repository:
For the CAD models, go to the Solidworks 2014 CAD direct link
A few of the models have built in support structures to ensure that prints will turn out fairly okay without needing to use automatic support in your slicer.
If you just want the printable files, go to the STL files direct link
Currently, the RepArm uses stock Marlin firmware, which allows it to accept gcodes. If there is ever a need for it, a fork of Marlin can be modified to suit the RepArm specifically.
To download the firmware from this fork, go to the MarlinRepArm repository.