Nav / Stereo Upgrade

[thunderX]

I've been searching for a week and can't find an answer to this, maybe you guys can help?

I have an '01 w/ NAV and no DSP.

I want to install an after market double din head unit and found the din adapter kit from Metra.

Here are the pics:

Plugs into CD Changer and/or iPod interface:


Plugs into NAV disc player and Antenna:


Plugs in the amp:


Here is the Metra Harness Adapter Kit:


Questions:
How in the world does this harness plug into the OEM plugs?

How do you extend the antenna wire to the head unit... I'm guessing an 8' antenna extension?

Thanks for any help.