AUDI A4 - Airbag warning light !!! HELP

I am going to by an Audi A4 2001 model, l was told that the car was 100% ok, but then l was told that the Airbag light comes on once in a while. What should l do ?? Is this serious ??

Also the dealer does not have a full history report on the car, he has told me that the car has been serviced by various mechanics, but there is no conclusive Service History in a whole 8 years !!!

How can l check that lm not going to be taken for a complete mug !! Any help is appreciated.