I think you could to black which is classic, or dark bronze metallic which is also classic but may highlight any flaws in the preexisting finish, but I don't think anything gray would work.

I would do black. As to sheen, that is up to you. Some (apparently your contractor does), like a high glass enamel. I would prefer semi gloss enamel, myself, and I have a few neighbors that use a lot of black, and they prefer satin. Its all individual taste. Which sheen do you like?

I would probably use satin or semi. Satin especially if in a bronze finish.

Thank you all for your ideas!!