I would've suggested claying for the overspray but if that's not working, then polishing, but only after thoroughly decontamination with iron/fallout remover such as Iron X, and tar/glue remover such as Tardis or similar. These will remove any embedded contaminants from the paint is a less aggressive manner, then follow up with claying, then machine polish. I expect the rust is iron deposits which decon should take care of. If it's proper rust then that's another matter all together.
On detailing product websites:
Look at CarPro Iron X and Korrosol for iron removers.
Look at Autosmart Tardis; Auto Finesse ObliTARate; CarPro Tar X for tar removers
There are plenty of others but that's a few pointers.