Q: Key and ignition switch fall out of steering column

While I was driving my truck, the key and the ignition switch came out of the steering column. After pulling off the road and parking, the key and the ignition switch internal parts literally came off into my hand. I couldn't shut the engine off. I called Onstar, but they couldn’t shut off the engine either. While it was still running, I had to have the truck flatbedded to the dealership. To discuss a different problem, sometimes the steering wheel makes clattering noises which are not connected to the wheels. There's a risk of the steering wheel locking up which would lead to loss of control. Also intermittently when turning the wheels, the instrument lights start dimming and flashing. Can you please tell me what is causing these problems and what I should do.