I was told that if you use or paint rust paint on a car over
rust spots and later paint over the rust paint with regular
auto paint, the auto paint will peel off. Some rust paints even
say on the label like "Do not apply paints containing strong
solvents over this rust paint", etc.

Why is this?

What should you do if you have a car with some rust paint on the
trunk and fenders?

Does rust paint really reduce the chances of the rust coming back
or would just cleaning the rust off and using regular auto paint
just as good?

Any advantages to using rust paint (besides not needing a primer)
and any differences between the brands?