Is there a way to get them without zen(cash?) if not does gold membership give you all of them?

there are a few outfits you can get without real money; some, like the Diplomatic/Dress uniform and the admiral's jacket you can get by ranking up (the diplomatic uniform is an award from completing the Diplomatic ranks, the Admiral's jacket for achieving Vice Admiral.) Sometimes, they have them for rewards, such as the veteran uniforms from the Vet rewards and the TNG S1 uniform from the TNG anniversary event. The Wrath of Khan uniform was available for free for a while (due to a marketing SNAFU before the game was launched) but they've gotten rid of that deal. Sometimes you can get outfits for ingame currency (there were ferengi outfits in the lobi store with the Ferengi lockbox and winter themed accessories during the winter event. The DS9/Voyager uniform set was available as a lockbox prize for both the winter event holiday box and the Cardassian Lockbox. You can still find the DS9 uniforms on the exchange for Energy Credits. But the DS9 uniform is the only C-Store uniform currently available ingame without zen.

To answer the second part of your question (as if it needs answering): no, golds do not get any of the C-Store uniforms for free, although, they do get a 500zen a month stipend, which they can spend on anything in the C-Store, including uniforms.

I don't think Gold gives many (if any) more costume sets. However, you can earn Zen points w/o having to shelll out cash. You can earn a currency in-game called Dilithium. There is a player driven Dilithium Exchange where you can exchange Dilihtium for Zen Points or vice versa. You'll have to grind a bit to earn the Dilithium, but you can get enough Zen points eventually to get anythingin the C-store.