The red slime is cyanobacteria. Here are a few links for some more info -
http://saltaquarium.about.com/cs/mic...a/aa092800.htm
http://www.lostmymarblz.com/75gal-algaecontrol.htm
http://www.reefs.org/library/article/c_bingman2.html
http://ozreef.org/content/view/26/2/
My guess is that the crab looks like a carnivore from what I can tell. Would need a better pic. It is probably a good idea to remove it.
The frogspawn is looking very healthy!
