Ok, so basically soft and LPS
corals. The small starfish you see are astera starfish. There are rumors out there that they will eat coral, but I don't buy in. Any member of a clean up crew can go rogue...but rarely and is usually just cleaning a dying coral up. It is their job afterall.
But in general, it is typical to see atleast one outbreak of astera stars during the life of a tank. After several years running now, I have one just beginning as we speak. They'll eventually die back down and aren't anything to worry about.
In terms of the red/purple-ish algae...is it really slimy and can be blown around the tank? If so, this is cyano
bacteria. A sign of nutrient issues in the water column.