Decent waterflow does help even though it looks like it would be destructive.
Did any of the skeleton break off where there's coral flesh? If so, you might consider breaking off that entire arm and trying to grow it separate from the main colony.
I would suggest skipping the brine shrimp and increasing the Mysis for the Tang. If you wash broccoli really well in hot water and then freeze it you'll have a good supplement for your Chocolate.
In my experience very high ammonia levels extend cycle time and kill off a lot of the live rock infauna to the point where the rocks become phosphate sources for filament algae. From research it seems that high ammonia levels is toxic even to nitrifying bacteria. This is not a case where more...