Specifically iron.
-
Yes. You'll notice in states located on the sea, specifically coastal cities and homes near a beach (especially in the northeast like Maine) things tend to rust faster if not treated or taken special care of
-
Try doing some research on "cathodic protection". In other words look at what it takes to slow down or prevent the process and see if you can figure it out from that perspective.
-
Yes, salt is erosive.
-
Yes.