Not sure about the metallic gray (Eduard refers to what I think is the same color as "dark iron"). It's definitely not steel though. If it were me and I were just winging it, I'd mix a dark gray with Aluminum and call it a day.
As for the metalizers, they're a specific blend of paint designed to replicate natural metal finishes. They're airbrush only (though I've been known to brush them and they're awesome for very subtle drybrushing). Some are buffing, and can be buffed to a very high shine. Others are non-buffing, and can't.
Metalizers look pretty great, but they're great weakness is that they aren't very durable at all and don't like being masked over.
On the Bench: 1/32 Trumpeter P-47 | 1/32 Hasegawa Bf 109G | 1/144 Eduard MiG-21MF x2
On Deck: 1/350 HMS Dreadnought
Blog/Completed Builds: doogsmodels.com