Gramma loretos and even melacaras are fairly easy to come by (at least here). Just imagine those would have been some rarer species like G. linki or G. dejongi - the latter will hopefully be available soon.
BTW, are you sure the crab killed the fish? Often they just eat them after they died. Though the male emeralds seem to be more predatory. I kicked my emerald male out after he took a bite out of some corals.
As for the anemone removal: if the rock can be taken out hang the anemone upside down over a bucket. The bucket should contain just as much water for the anemone's foot to be out of the water. After a while it should just drop off.