A cast iron railing is a metal railing.

It depends on the context. If you're talking about a railing like alongside of a staircase, then that is a noun. If you are talking about someone railing against their fate, that is a verb. You can also use it as an adjective if you say something like "The railing paint is faded."

Curtis Railing's birth name is Lulu Vass.

There is a railing around the cupola.

Curtis Railing died on May 6, 1952, in Haverstraw, New York, USA.