The trading volume of MAY in the last 24 hours very low, does this say about coin is still being developed? Is octaex.com available for trading?
Volume of MAY is nothing to be concerned about. If you're worried check out Truckcoin, and Version coin and look at there recent pumps. They had very small volumes of less than a 1000$, sometimes just double digits for a good few weeks/months and still managed to pump.
May is worth investing into because of the block rewards. Also a low supply of 100m, which means when it pumps, it'll pump good. Although I do think the dev should be a little more active, via twitter., discord.... whatever.. or at least do some more commits on github. A lot of people pay attention to these little factors in determining what to invest in. Personally I don't care about the latter.. but an active developer makes people feel more safe buying into their coin.
I do think it should be rebranded and drop the Theresa part though. Just May coin seems more.... attractive. Theresa makes it come off as a joke.
As for your other question I'm not sure, never heard of that exchange.