Rust repair, what kind of primer etc would work?

[Crille]

Hey there,
I have my 2008 XC90 that I've owned for 1 year, It's in a really nice condition overall. When I serviced it for the first time I saw that there was a little bit of surface rust here and there, also the rear suspension parts were completely covered in surface rust and worse on some areas.
A lot of salt here in the winters which takes a toll on the car.

I decided to just do a quick fix/protection or whatever last year before the winter. I used a wire wheel and other tools to remove as much as I could. I decided to just spray everything down with a undercarriage spray, a sort of elastic rust protection film. I realized in hindsight that it's probably not enough. But oh well, maybe it at least offered a little bit of protection on the suspension parts during the winter. It has come off on some places.

There were also some slight surface rust on the body of the car as well on some areas and maybe I even made it worse by just going over it whit the wire wheel and spraying the same spray on it? The spray remains somewhat sticky and elastic so I guess I should have needed something else like a primer of some sort. I haven't really done any rust repairs before.

I was planning instead of doing it properly by removing the plastic sill covers, since I don't know what it looks like under there. Also removing the rear bumper and really any plastic trim that I can to check the hidden spots for rust.

My question is how I would go about this process, will it be enough with a wire wheel on a grinder/drill to remove surface rust? Maybe some flap discs, sand paper etc.
Once the rust is removed in these hidden areas what kind of primer and/or paint should be used to cover it up for the best result in your opinion?

For the more visible areas under the car that run the risk of being hit by rocks and other debris, maybe It would be okay to use something like the undercarriage compound/Sill protection compound that I used last year. But perhaps I should protect it in the same way with a primer of some sort before I do so.

Thank you in advance.

[Krons]

I have typically wire brush the loose stuff and use Corroseal rust converter. Then paint and/or apply Fluid Film to prevent future rust.