To prevent rust, try not to keep the item in damp conditions as this will not help. WD40 can also help prevent it from getting worse. If you can or know someone who can do it for you, welding is a good idea.
they can apply paint to the iron or steel to stop the rusting of the car
There are material available that convert rust and stop it from spreading. In Australia it is called rust converter. Tel your hardware supplier what you are looking form and I am sure he will guide you to it.
the metal piping in your car will rust much quicker if you did that so no
Rust is broken down and prevented from spreading further by using chemicals called rust converters or rust inhibitors. These chemicals react with the rust, converting it into a more stable compound and forming a protective barrier to prevent further corrosion.
You must cut out all rust, because rust does not stop it continues to grow, please do not just cover it up because it will come back again. The questioner is asking: How do you refurbish a well used car? and telling you that the car has rust all over. It would seem that the first thing to do is replace the parts that are rusty.
we can stop spreading by giving tt to a child
Washing doesn't stop rust to return.
with no weld use fibreglass cloth and resin spray stop rust on body to halt rust process before
Car magnets doesn't cause rust.
Look for an anti rust spray.
Kill rust, or direct-to-rust primer and paints, do not actually "kill" the rust, they encapsulate the rust, preventing oxygen and moisture from contacting and spreading the rust. Unlike other paints, they are impervious to moisture and that helps to considerably slow the growth of rust.
just start pulling cutting scraping and a LOT of sanding to get ALL the rust off the top. Then put a rust stop primer on it before anything Eal's.