Aftermarket stereo install q's

I just purchased this Pioneer unit for my '03 SE:http://www.pioneerelectronics.com/PUSA/Car/CD-Receivers/DEH-P7400HD

I also have this coming as well:http://www.metraonline.com/part/99-7417
Curious as to whether the stock wiring harness that connects to the old Rock Fos unit will mate up with the new unit? There's also plug-in points on the back of the new Pioneer unit for steering wheel stereo controls and for the antenna.
Will I need to purchase any other adapters for this particular install?
Thanks in advance for any help!

the mounting kit you ordered is correct, axxessinterface.com will have what you need for steering wheel controls. i am not 100% sure on the power harness adaptor but it looks like a standard nissan adaptor for rockford or standard radio re and re. just be sure to hook up the amp turn on wire (blue wire with a white tracer stripe). if you like fm radio the pioneer is a great choise for its stronger than most tuners. i am a car audio installer but have not done any xterras since they were still new to the market. also some nissans used a double diversity antanna and you will need the adaptor for that too. hope this helps. new here and as far as i can tell i will be owning a 1st gen xterra within two weeks...fingers crossed

I wanted to install a new GPS Dash on my 2012 model, but not sure if it will void the warranty. Do you know if it does.