I believe I had a 25ft 4 gauge for power. You can run a 4 gauge through a hole right near the hood release cable- it will fit fine and you can even use the stock rubber grommet- just open up the hole a little more for the cable to slide through. For the ground, use a 0 or 1 guage and make sure it's not longer than 18". I originally ran mine with my power run up to the battery, and had some alternator whine. Read online about my mistake, shortened the ground, and now the noise is gone. My amp is in the rear trey area- you'll have to unbolt a support bracket, but other than that it will go right in and is a perfect spot. The amp turn on just needs to go to your head unit, so 25ft will be more than enough. RCA- same.
For reference, pics of my install can be found at:
Remember to also tie in your power antenna lead to the blue amp turn on wire as well so you can get radio reception. tires sport cars The Armada's antenna are in the rear windows and require power to work.
Good luck, and post some pics when you're done!