ehser1:
I think you've got a good start to your clean-up crew...I wouldn't want to add too much too quickly. Urchins can be great a eating algae, but need a substantial amount to thrive. It's probably best to wait until (if) you have an abundance of algae before adding one. On a side note, many of them are known to eat coralline algae as well, which most people believe to be desirable.
As far as the shrimp go, the cleaners are great to watch, especially at feeding time, and are pretty hardy. Other than that, they will scavenge some, and mine have cleaned a few of my fish over the years. Honestly, they are really cool and I will probably always have them in my reefs, but I've never considered them part of the "cleanup crew"...