Get a magnet - that should solve some of your questions.
There are some SS parts on the car but not very many. Door and trunk locks come to mind. A lot of the trim is chrome plated brass or chrome plated steel. The rest of it is anodized aluminium or pot metal.
Pot metal can be tricky to plate because it will often form small pits under the plating. Once the chrome is removed you will be able to see most of these pits. By the time you grind, polish, fill, and plate, there will be nothing left of the original shape. I've seen trunk stars which had no sharp edges from being re-plated. Get a new one - it will very likely be cheaper.
Door handles and the front star are two places where you can save a lot of money providing the parts are not junck to begin with. Always price new parts and compare that to replating before spending a lot of time and energy on plating.
Anything that was anodized should not be chrome plated. These parts are usually quite soft and will bend easily while chrome won't; so you can expect it to crack and start peeling off after a while. Besides, it doesn't look right.