Clowns would be a good choice. As far as a clean up crew, be a bit cautious about how many and what. It is common to buy so many snails etc per gallon, but this isn't a good idea IMO. There is only so much food to go around, and often most of the crew starves to death.
A water change at this point isn't a bad idea, but stability is key with long term success. If you were to do a water change at this point, just change water, don't go crazy and gravel vac, clean filters etc. Your biological filtration is still new and relatively fragile at this point. Not to scare you, but messing with things could potentially do more harm than good.
You'll know when it's time to go in for a good clean when algae starts going bonkers. At this point I would check Nitrate and see where you are. Maintaining a low, but moderate level of Nitrate (3-10ppm) is actually a good thing. Shooting for zero as many people seem to be doing these days has actually been shown to be more of a negative than a positive for coral growth and coloration.
"New tank uglies" are common at the point where you find yourself now and in the near future. Things like Cyano can be pesky, but all part of a new tank. Things will mellow out over time.
Keep asking questions, you are in for a fun ride..