What does gold filled mean compared with gold plated?

Gold filled has a thick layer of 14k gold mechanically bonded to a base metal, while plating is a thin electroplated coating. Gold filled resists wear and tarnish far longer and can last years with normal care.

Will this chain tarnish?

Gold filled is much more resistant than plating, but the clasp and jump ring are common wear points. Keep it away from perfume, chlorine and sweat, and wipe it after wear to slow any dulling.

Is 3.3 mm thick enough for a man?

It is a middle weight. It reads as a real chain on most necks but is not a heavy statement chain. Men who want a bolder look usually go wider.

Can I wear a pendant on it?

Yes, the Figaro links are open enough for most small to medium pendants, but check that the pendant's bail fits over the 3.3 mm links.

No. It is 14k gold filled, so the gold is a thick layer over a base metal core, not solid gold throughout.

How should I care for it?

Store it dry and separate from other chains to avoid scratches, and avoid wearing it in pools or showers. Wipe with a soft cloth rather than polishing abrasives.