2003 Ford KA mileage gage resetting, airbag light on & other problems

Hi I have a 2003 ford ka and yesterday my mile gage started resetting itself to 0 every time I restarted the engine, a clicking noise (like the sound of things resetting) also comes from where the mileage gage is when I switch off the engine. The airbag light has come on and stayed on. The speedometer has also stopped working and is stuck on 20mph at the moment. Also, the CD player keeps flickering on and off but the radio seems fine. A few friends I have spoken to say this may be an electrical fault? Last Friday the air vents started blasting hot air out when I didn't have the fans on and the heat was set to cold but this stopped half way through the journey, topped on coolant levels on Sunday just in case and it drove fine. Last night (Tuesday) the blasting hot air out the vents started again and all the other problems listed. Any advice would be greatly appreciated!!