No idea where to begin!

Yea I figured the door could be fixed. Okay so I take it a need to buy a da sander and a grinder to get started on those areas, as well as a welder and some sheet metal, fix the rust spots first. Then do I sand the whole car? I bought a block sander as I read those were necessary, can I sand these areas with that?

By taking it all apart you are taking the glass out right? After fixing the rust areas and any dents sand the whole car down with the DA, block sanding will come after the primer coats are sprayed.