can I buy stratis on bittrex exchange? I have all my btc there! Is it safe to withdraw?
Sure you can. Yes it's safer to keep STRAT in your wallet, preferably ledger nano S, than leaving them on any exchange.
Yeah, if you have any significant amount of STRAT, please don't leave that on exchanges. Transfer to your personal wallets. Also, if you have a bunch, you can get PoS rewards which exchanges don't give you.
If you have 25k-30k stratis you can earn about 1 sratis per day if you stake the coins. If you have less than that lets say <10k then just park them in an offline wallet. The best is Ledger Nano S but there are a few other wallets allready available to you eg. tradtitional qt wallet (c++), new full node wallet (c#), Breeze wallet. All of them will be better than an exchange wallet as you own the private key. Just remember to make a backup of your wallet file.