If you car is like my 8th gen was, even though i had a manual transmission, the plug to light up the shifter console if the automatic was present. you can tap the illumination wires there, or pull them from the stereo or hvac controls.
hog rings were what was used on the 8th gen Si, plastic clips was non Si models, no idea what the 9th gen is using. In some ways the rings are easier to use than the clips, but you will need a set of hog ring pliers to close back up.
i dont know if anyone has the full service manual for the 9th gen out yet, i would check ebay and see if any vendors have the digital copy of the manual for about 30 dollars.
tapping ignition switched circuits, you just have to be careful, the add a fuse devices do have limits of how much you can put through them, both the circuit youre tapping and the one youre adding, (ie you cant put a 10a add on top of a 15a)