Might as well launch your exchange and implement that feature so we can test it and we can give feedbacks coming from our experience, all the exchange I've seen are all the same, but even if your exchange is different, be sure to concentrate on security and support, every trader ask high priority on these two.
Definitely no ICO of any kind and no token is required to make the system work. Understandable concern though considering people will try to shove a token in to anything now for a quick buck, even if it hurts the efficiency of the system its in