1- is my site showing up as century Gothic
No.
or sans serif?
Yes.
2- is century Gothic specific to a certain OS?
No, it's not included in any OS. It is often installed by MS Office.
3- is there any improvements in the css that could load century gothic
You could use @font-face embedding to have recent browsers download and use the font. Unfortunately this isn't allowed for in the usual Monotype license; you'd have to get a special embedding license. Which may not even exist for that font.
(possibly different filenames/font names for the same font?)
No, the Monotype edition is the only variant I'm aware of.
If you are set on a geometric sans, you could try including Futura ("Futura", "Futura Std", "Futura LT Medium", "Futura Md BT", "Futura No 2"), Avenir ("Avenir Medium", "Avenir 55 Roman", "Avenir Next LT Pro"), or even Avant Garde in desperate times. But none of these, or any other geometric, are bundled with operating systems, so you have a pretty small chance of it working.
Do I need it in quotes too?
Yes.
Best Answer
Here's a good tutorial on how to include the font file with your website so that other computers that don't have the font can grab it straight from your server: http://www.miltonbayer.com/font-face/
I would also seriously suggest looking into Google Web Fonts which does all of the work for you.