No idea where to begin!

On the corner of the roof, when you pull off the chrome trim the rust will be more extensive than it looks. Hit that with a wire wheel on grinder and it will find the rusted thin metal. Do that wire wheel on areas that are suspicious and you will know what you have. You have to get that rust out or it will grow from backside of the paint. You need access to mig welder. AMD or others have most patch panels for the usual rust prone areas. Look really close at lower corners of windshield and rear window frames, those are often hidden by trim pieces.