Um, I just bought 4 feet of the RGB wire.. it's real cheap so just buy a bunch extra.
That switch should work fine... I had to change the fuse on the switch I bought, remember LEDs have a very low amp draw.
And that was the fuse tap I used also... typically you could just shove the wire down with the fuse but a tap just makes it a bit nicer.
There's a couple good bolts under the stereo you can use for a ground... the panels on the side of the center consol come on and off easy.