Trust me on this, i have a 4" flame angel in my 37g mix reef and he swims laps around the tank all day, he would fight my ocellaris pair all day because they took up a 1/3 of the tank in their territory. Then i moved the clowns to my 20 long and the angel is going in my 60 cube. Heres what ive got in my 37 fish wise ATM:
~Bonded pair of purple fire fish
~Valentini puffer
~Starry blenny
~flame angel (going to my 60)
Royal grammas need to be QT because they are very suseptable to flukes, i would wait for the tank to mature before adding a mandarin so that you can build up a large amount of pods, but everything else sounds good. 5 fish is the limit in that size.