The keyfob works to lock and unlock the door intermittently, and I have recently changed the battery so that is not it. Along with this, the back latch sometimes continues to click when it is open and the car is parked. The interior lights stay on. The back windshield wiper and washer fluid don't work, the lights on the radio and temperature climate control display don't work nor do those items. These are all problems that are intermittent, every one of them, no pattern as to which are going to work or when. The car runs fine, there are no mechanical issues in the running of the vehicle. The problems all started happening about the same time, within a week or so. Could it be a loose wire or a module? If it is a module, what module is it and how easy for a non-mechanic to replace?
You need to find out what is causing the problem and I would suggest by starting with checking for bad ground circuit connections. Since the rear portion of vehicle has more problems than others, that should be the area to start with.
Another thing to check would be the fuses and their connections. Sometimes fuses heats up and this can result in poor connections over time so it would be good to try pulling out fuses and checking for signs of overheating and oxidations causing poor continuity.