Regarding rust, I saw an interesting sight way back in the 70s when I lived in Swindon where Pressed Steel Fisher had a plant which turned out car shells in raw steel. These were then shipped out to places like Oxford where car manufactures were based.
Owing to strike action, bodies were stored in the PSF site for some time (out in all weathers of course). So when things got moving again, instead of seeing loads of shiny bodies heading out, we were treated to the sight of very brown (rust) bodies instead. Presumably they would be treated at car manufacturers before painting (but I wouldn't bet on it). I often wondered how owners with those cars fared rust-wise.
[Footnote: I can't remember whether the strikes were at PSF or car manufacturers, I think it was the latter]