Hi Ray, I'll take a punt the problem is a failed earth/neg return circuit. probably where the erth/neg wire contacts the body work some rust has developed. the path of failure all points to gradually deteriorating neg return circuit, the loss of wiper park is a common problem associated with a poor earth/neg contact.
look for the colour code of the neg wire in each failed piece of gear, make a nice siny contact on the main body, the door latch is a good one, run a wire with clips from this earth/neg return spot to the neg wire at any of the failed bit of equipment, one with a decent size cable would be best, now see if it all works again. If that works, trace down all the earth/neg return points (a bolt with a heap of the neg coloured wires attached), take the bolt out, clean up the metal to metal contacts, a good dose of electrical contact paste or grease if you don't have any of the contact paste, then bolt it back on. you will need to track down every earth return point and do the same thing or you will be chasing weird elkectrical problems for ever. The door light switches stuffing up the interior light, central locking, thenalarm malfunctioning is a trap for the inexperienced

it's just a simple neg contact to the body so it get gunked up quite easily, it only take one crook one to cause all sorts of problems.