Dash lights suddenly going out

I inherited my dads clean low mileage SUV. He had some issues with the dash lights suddenly going out. He took it in on a few occasions and they couldn't find anything. When I got the truck, the door locks would randomly go up and down and then on the driveway the horn would toot and the locks would go up and down. My husband checked the fuses and they were fine. I tried replacing the batteries in the fobs because I heard a low battery in a fob could cause similar issues, but it didn't work and I finally just stopped using them. Also, the tire pressure sensor monitor service warning is coming on and he had that problem too. I read that the windows and locks and sensor monitor are on the same transmitter. I also read something about updating the software for a computer module, but I'm hoping I can start somewhere easier. Also, when I start the car and idle for a bit in the driveway, the interior lights kind of flicker with the engine and when I drive I can see when I accelerate the headlights do too. What is up?