http://scosche-cars.com/
That site will allow you to find the installation accessories you need.....
Since you already have an aftermarket head unit you probably won't need the antenna adapter or wiring harness plug...
The standard radio is 1.5 DIN, not many aftermarket choices. You'll need to use a single DIN unit....I looked up the Pioneer KEH-1500, appears to be a single DIN cassette unit, so I assume you already have the adapter to install it.
Curious, what are you going to use the USB port for?
TOC Admin
Brando