It is always a good move to start at what is not working and work back instead of looking for the cause from many points going to the part that is not working. Keep working until you find power in this instance, the trouble is these cars are so tricky electronically it could be the last thing you would think of.
In this case with so many problems it would appear to point to a part that has a hand in controlling a lot of components, I can only think of one and that is the BCM. I will study the wiring to see if that is a possibility.
When was the last time you started the car successfully?