With such an exchange as cryptopia and bit-z - there is no future for the coin! Every time there is a problem with the resale of coins with a deposit.

HitBtc is working great!
I'm not sure how.. they have only 1.5% of the volume. That can be a very long wait.. looks like more than 2-3 minutes between transactions. Less than 3BTC per day.
The only time you'll wait long is when your ask/bid price is way lower/higher than the prevailing price. But regarding on how quick a transaction can be completed, I don't think it is relevant to the trading volume. We will see the real trading volume I guess when the airdrop ends.
Lots of people had problems withdrawing coins from hitbtc including me. I am not sure if it is solved by now but i stay away from them.
Never had a problem with them especially BTX transactions. Just stay away from doing trades/exchanges when the site is being DDoSed.