(I've emailed this information to CDG, but for anyone else who finds this thread...)
Everything you want to know about removing the factory radio and installing a new unit (including a wiring diagram) is detailed here:
SVX Audio Installation Guide
The document Earl listed above describes a few additional steps necessary to "transplant" a factory head unit from other late-model Subarus into the SVX. Earl is in the process of posting an updated version in which I corrected a few problems. To find the latest version, go to this folder in the How-To area:
Folder: Stereo Speakers & Antenna
and get the document "WRX Stereo Install" [updated version is there now]
As for the antennas, the coax cable with the male Motorola plug is the one from the motorized antenna. That's the correct gender that will plug into aftermarket HUs. See my guide for more info.