Yellow tail damsels are not aggresive. Blue chromis are just as nice as the green. Just watch that you don't get a damsel group that is territorial like blue devils etc!
Someone above metioned peppermint shrimp! I think that they are they best fighter of rock anenomes. If you buy a few (they are extremely cheap to purchase) they will clean your problem up in a short period of time!
I think more live rock up to the top is nice. It gives more places to put corals as well. Lots of mushrooms. I would get rid of the hair algae if that is what the green stuff is too!
My toadstool is right at the bottom of my tank and it is doing just fine! The polyps are all the way out everyday and it has doubled in size since I got it! IMO in the pic (although not that clear) It looks like it is fairl healthy!
The above is right! It is a risk! The flame angel is known to chew away at corals so I don't see why they wouldn't take umbrage on a clam! It is a chance if you want to take it!