Yes, car wax is also suitible for gelcoat or urathane paint on boats.
Yes, but it is water proof and stronger.
No, but you need to use special ski wax, available from many ski shops. Alternatively, you can take them to a shop to be serviced
First, wash the car with lots of soap and water. Then dry the car to keep from developing water spots. Anything left on the car after the wash will show up under the coat of wax, so try to get it as...
YES .Maybe some waxes destroy paint, but there are waxes specifically made to protect car paint.
Preserve the paintjob.