It will need to be sanded to remove the rust. The original paint if in good condition will only need to be sanded to allow the bedliner to stick and hold to it. Any bare metal should be primed at the very least and receive a coat of paint to help protect it. As you have seen there are many brands out there. You really only have one chance at doing it right so a quality product is mandatory if you plan on keeping it for more then a little while. Ive used DuraBak with excellent results before. Most products will fade after a few years. (black) Monsterliner is often online here and sells a good product.
Myself I would start with the floors first. Then go from there. I would also stay away from the products in a spray can.
Of all the things Ive lost
The one I miss most is my mind
Its like a fart in a windstorm
It smells good but thats about it
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