Is Futures the only way to short an asset with a margin?

Hello,

I'm sorry if this is a stupid question but I really couldn't find an answer anywhere, so I'm asking here.

So here's my situation. I've created a bot which (hopefully) systematically predicts small fluctuations of some small-cap coins. Now, I tried trading these coins through the Binance Futures API but unfortunately for 95% of these I keep getting the response "Invalid symbol". When I tried future-trading some of the bigger boys like "BTC" or "ETH" the trades register without a problem, so I inferred that not every coin listed on Binance could be futures traded. So I actually have 2 questions:

1. Is my guess that not every coin that is listed on Binance can be futures-traded correct?

2. If that's the case, then can I for example "Short" an asset with a margin, through any way, other than Futures?

Thank you!