In most states yes, it is illegal :)
no
Yes.
No.
It is illegal for a car dealer to sell any car with non-functioning air bags.
There are federal regulations mandating that cars sold/traded in the US past a certain year must have seat belts and airbags. If you were sold a car(1993ish or higher) and it doesn't have an airbag then chances are the vehicle was totaled and repaired. If the car was built before airbags were required by law, then the car can be sold without airbags. Otherwise it is illegal to sell such a car.
Well no if the modifications are illegal.
No. There are federal regulations mandating that cars sold/traded in the US past a certain year must have seat belts and airbags. If you were sold a car(1993ish or higher) and it doesn't have an airbag then chances are the vehicle was totaled and repaired. If the car was built before airbags were required by law, then the car can be sold without airbags.
Yes, it is illegal to sell a vehicle, that came equipped with a catalitic converter, with the converter removed, in any state.
What does the converter convert a Cadillac to?
You must sell and advertise the vehicle "as is, where is" otherwise the sale is illegal.
no, the distance the vehicle has covered must not be changed as it will be incorrect if you ever sell the vehicle and is therefore misrepresentation and that's illegal.
Yes, but you must tell the potential buyer that it is missing. That it may be illegal to drive the vehicle without it.