Not too sure about your horn, but to turn off or reset your airbag light, you need to go through this process:
Open drivers side door, but press and hold the little door sensor (so the car think the door is closed), then turn key to ignition without starting the car, then quickly press that door sensor at least 7 times and just hold it. Then just turn car off.
But it does sound like theres something wrong with your steering wheel.