Try not to stir up the substrate when you are draining the water. If you can mix up a fresh batch of half the water volume at the destination then you only need to transport 50% of the tanks volume; hence, 50% water change. It wouldn't hurt to attach a filter sock to the end of the hose where you're filling the transport. Once the water has been reduced 50% and you are satisfied with the amount of water saved you can begin to carefully remove liverock. The slower you make this part of the process the less debris you will stir up. Place the rocks in either rubbermaid totes, trash cans, or cardboard boxes lined with styrofoam. Once the rock is removed the water level should dip low enough so that there is little chance of the fish escaping. Place the eel by itself, sailfin tang and "nemo" ocellaris clown and coral beauty together, the niger by itself, cinnamon clown and rabbitfish together, the urchins together, and the sea star by itself. You may want to use a container to catch the foxface so its dorsal spines don't get caught in a net. I would use 5g buckets or rubbermaid totes for their transport with portable/battery air pumps. Do you plan on keeping the sand or purchasing new? The sand will have to be thoroughly cleaned before adding to the system once moved. Either case, you can use a large diameter hose to suck out the sand and/or a dust pan, but if you plan to purchase new you can use a wet/dry vacuum to suck it out quickly. I've broken down larger tanks in 2-4hrs or less if you plan accordingly and work swiftly. Is this tank going upstairs? If so I'd have a contractor inspect the area, but if this tank is on ground level I don't think you'll have anything worry about.