As far as the rear A/C goes it's doable, but a pretty big job. I retrofitted everything into mine, and everything works fine, with the exception of me still needing to hook up the rear low pressure line which is its own story. For the A/C you'll need to obviously drop and cut the headliner for the vents, procure a wiring body wiring harness, which is pretty expensive, to get the wiring off of as it is not there in non rear A/C trucks. You can also make your own wiring which is what I did.

Installing the actual rear blower motor and ducting is one of the easiest parts of the job, and is pretty self explanatory once you have the truck apart. You'll have to remove the Intake manifold so you can swap in the new refrigerant lines that T off to the back, not a huge deal, but something to be considered. After you have the new lines under the hood, running them to the rear blower motor is also fairly easy, aside from the pain of getting the lines into the correct spot in the first place.

You'll also need to factor in the cost of having your system properly evacuated and recharged, which is a few hundred dollars at a shop. Hope this gives a little perspective to the A/C portion, the seats and stuff should be fairly easy in comparison.