It looks like the corrosion is only surface deep. This is normal for SS 304 actually.

Autosol is very fine polishing paste which is more on to give shine to dull surface. I have not much knowledge of what available out there. I would start with something more coarse like household Jif/Zip/Cif whatever to remove the corrosion and then finish with the Autosol.

Polishing machine would help. If not it would be hard on labor . I use a grinder with polishing pad installed, but grinder speed is still too fast even at lowest speed. That is why proper polishing machine is better. Too high speed will heat the surface thus can change the surface color.

Yes, polish pad attachment to drill is easy to find. I also have this.