1. Are all these coins in my waves wallet legit? Or some of them are fake coins?
Not sure about it, though some of them might be worth it if traded.
2. What do you guys do with these coins? Also there's a name for these coins. I believe they are called airdrop correct? I notice i also got a very very tiny amount of btc and bitcoin cash here. Does anyone know why did i receive it? By little i meant like pennies worth. Is it due to leasing or just having waves?
I'm not doing anything since most of the coins have no value/no volume in WavesDex. You'll receive airdrop coins as long as you have waves in your account.
3. Can someone who have all these coins and traded them tell me what is best to trade it for? Thus for btc? For btc and then usdt?
I have the coins, but the only coin I traded for BTC is Mercury. Aside from WavesDex, MER/BTC pair is available in other exchanges too: Bittrex, Tidex, and Upbit.