Yeah, the bright red and bright green things should be mushrooms. Amphipods for sure, not copepods, though sometimes I use the term interchangeably myself even though I know its not right.
+1 on the sponge identification... at least that what it appears to be to me.
Asterina star for sure, they are harmless. People report some species eating zoas but in my opinion, thats just because the zoa went downhill already and the stars are just cleaning up the rotting polyp. I have 100s in my tank and a ton of zoa polyps. The only one's I have ever seen eating a polyp were on colonies that were going south already. If I have zoa eating stars, they would have cleaned out that colony and then moved onto a fresh colony. They never do. Just my 2 cents though and just speaking with my own experience. Somebody else may have a killer asterina starfish amongst their tank inhabitants!
-Ty