The wiring that comes with these is maybe 18" long, so i used a roll of 18 guage speaker wire to extend.I didnt do any lights for the rear footwells, as i have the motorized seats which i didnt feel like dealing with, and also dont have any kids or rear passengers so i felt i didnt need them. Gabekalp did install rears, so maybe he can chime in on this portion.
As far as running wires go, once you remove the door sills/kick panels (they just unsnap pulling upwards and toward the rear), running wires is extremely easy. I just fished my wiring below the carpet which comes up very easy with the door sills removed.
Now as far as the rear switch goes, you wouldnt want to tie into the cargo light circuit as this doesnt work when the truck is moving, so i would probably just use a seperate toggle, powered by a switched 12+ source. Maybe like the wipers, or radio ignition lead.