never use it..
i choose huobi because they never get hacked
All centralized exchanges could be hacked, Huobi could also be hit at some point. So never use centralized exchanges to store long term money, use personal wallets.
Yes. The best you can do it to deposit coins, trade them and withdraw. This way you minimise chance they rob you out of your coins. You would be very unlucky that hack happen in that hour you are doing your trade. You would be so unlucky to be able to win a lottery.