The pink/purple stuff on your rocks could be coraline algae. This is a good thing and something you want to encourage. It's the reason you have LR
in the first place. This will help your filtration process.
It could also be red-slime algae, but as the name suggests its more red/purple then pink/purple. It is also usually a stringy kind of covering, whereas coraline algae is more of a crust type covering on your rocks. If it is this, then you might have a nutrient issue in your tank (too much phosphate is a common cause), or too much light. The best way to remove this stuff is to remove the source of your nutrients or reduce your lighting schedule. If you are using tap water, test it for phosphates. I had a red-slime problem and this was the source. I was able to get rid of it by switching to RO
As for clean-up crew recommendations, I would check any of the sites out there that offer "packs" like the previously mentioned liveaquaria.com, or justphish.com. You might want to start out with a pack for a lower sized tank (i.e. 25-30gal), and then add more as you have a need. The key is to not get too many critters and then have them all starve to death.