Hey Dogga,
The wiring was already attached to the LEDs and ready to connect. You make a valid point about the existing wiring loom because there are some empty slots in the connector that could possibly be for CW side mirror connection. In my case I tapped in from the original indicators. I had it done so that both sets of indicators light up, but in recent times I took the globes out of the original indicators to stop them from lighting up.
The casings originally arrived already painted in same colour as my previous i30 (steel grey). So when I ordered my new white one I had it painted white. So in other words you can specify what colour you want from the supplier.
I ordered my LED casings from Hi-Motors; use this link if you want:
http://hi-motors.com/When ever I want something I go to these guys first. The products they have are about half the price than other websites like Shark racing, whom I have also dealt with (LED lights, etc). But I can't remember the exact price. I think it costed about US$60, so whatever the current conversion rate is. But you will need to include shipping cost, and I think from memory it costed about $90.
If you are interested in buying from then let me know because I'm interested in picking up some LED Door scuffs. That way we can halve the shipping cost between us, provide you live in Australia of course.