I've been trying to figure it out as well, there is an empty plug on the frame behind the bumper, kinda under the driver's side tail light. From what I've heard the is the plug for the lights, so I think I just need to find the harness, switch and lights. I have not dug into it much yet. I know...
I don't know about the rear seat covers, but I will say the rough country front covers fit really well, and seem to be decent quality. I would assume the rears are the same. I've had them for about 5k miles now.
I bought the rough country bed mat while I wait to get it lined. I'll probably still use it after it's lined as well. I was surprised how good it is for the price. It's thick, and it's rubber, not some harder, plastic type stuff. I would definitely recommend it.