Awesome updates! That crab looks evil 

... maybe the chaeto is a ghillie suit I’m which he uses to ambush unexpecting prey.  I love the mandarin fish! Super jealous.  I tried one way back when I had my 75g but he got so skinny and eventually died.  I tried so hard to keep him alive spending a couple $100 in pods added directly in but it didn’t work.  
It’s nice to see yours is doing well.  I’m too scared to try another one, sometimes I look at night to try to count pods to convince my wife the tank is ready.  I have also heard of some mandarins eating frozen mysis (probably hard to get).  
Following along! Looks great.