If you fancy more shrimp, consider fire shrimp too.  They're an amazing colour, and another type of cleaner shrimp.  Mine live happily with the skunk cleaner shrimps.  Maybe one of each?

I've never tested or dosed iodine.  The shrimp molt all the time.

Also, all my shrimp clean my fish.  The fish tend to present themselves, but sometimes the shrimp jump them - funny to watch!

I have an emerald crab that spends all day picking algae off the rocks.  Some say they have been known to attack fish, but they are scavengers, so you'd expect to see them all over anything that's dead or dying.  As long as there's algae to eat, I doubt they ever bother looking for anything else.