Hi Lindsay,
Warranty's will vary depending on the dealer, but I can tell you now that Northshore Prestige's warranty is pretty damn good.
Won't cover general wear and tear item like tyres, but stuff that should be working correctly (boost gauges, rear hatch locks etc) are dealt with quite well. Even if like me, you don't live in NSW.
One general problem to be mindful of is the turbo... It will let go, just a matter of when.
$2500 per headlight is what I have been quoted for a new item from Nissan.
This for the Xenon units, the Halogen headlights are a bit cheaper although still quite expensive.