I'd be hesitant to buy lights from RR, or any other company that doesn't specialize in them. Maybe it's just me. I had a pair of off-brand lights on a previous 4x4 and had all sorts of problems with them...leaking, wiring problems. Though that was about a decade ago, and I'm sure modern versions are much better.
See this thread: Windsheild Lighting
If you're thinking of mounting them on the windshield, make sure you go with driving or long-distance lights; fogs will just throw glare on your hood, and should be used on bumper mounts.
As far as wiring them in, any decent lights should come with a harness, relay and switch. Just pull the appropriate plug on your firewall, fish the switch wires through with a coathanger, hook the harness up to the battery and ground it, and you should be good to go.
Some peeps cut off the switch that comes with the lights, and install a series of switches in the A-pillar or dash. I use an sPOD, which mounts the switches at the top of my windshield. Some examples:
The switches that came w/my sPOD (which makes hooking up aux electricals very easy...good, cuz I'm an electrical retard.)
I like to wrap any exposed wire in the engine bay with heat-resistant conduit, then zip-tie it to existing wiring, to keep everything clean and protected.
On this Jeep, I initially had KC SlimLites...they were great, light-wise, but I didn't like the way they blocked my vision when I was turning left across traffic. So I switched to the Rigid Duallys, which are much smaller, brighter, and have very little current draw (but cost a lot more).
KC SlimLite 100w Super White Driving Lights:
Rigid Dually LED lights: