As for where to put the livestock. In my opinion, rubber made tubs, kiddie pool, look on
amazon for larger rubbermade shallow 100 gallon tubs. (used for many things such as outdoor stream beds, etc. ) But, transferring the water to the rubber made tubs, some rocks, and then catching the fish and putting them into 1 or 2 tubs (depending on agression etc). Make sure you add heaters to the tubs and place them out of the way of where you want the new tank. If you have corals. It'd be nice if the LFS could house those for you temporarily if you have a good relationship Otherwise you'll need to find a way to mount a light over the tubs for the corals. I have a friend that had a 50 gallon burst on him in the middle of the night. There was no warning, the glass cracked and everything landed on the floor.
He woke up to it and him and his wife were picking up fish, and corals and placing into tubs with fresh salt water and heaters. In all of it he lost one fish! He had them in heated tubs oxygenated and with circulation pumps until he got a replacement tank setup for 2 months.
The key to this is don't panic, think through what you're livestock need to live. Heated and oxygenated water and bacteria. Pulling your rocks, provides the filtration and placing them into tubs. Pulling the water and the heaters keeps the chemistry the same. then it's just netting the fish and/or using buckets to catch the fish and move them into the tubs. Siphon the remaining water into the tub(s) and rock work. Move the lights. Now you can do whatever you want to the old tank...
It's a pain in the butt, yes! But, insurmountable, no. If you take your time it's not even that bad. Just make sure you have a plan of what equipment you're going to use to maintain life in the temporary housing. Once you have all the equipment planned out, it's easy to move the livestock.
I had another friend that had done a tank tear down to redo his plumbing... He seriously kept the fish and rocks in a kiddie pool (hard sided) in his living room until the plumbing had cured. (about a week). Fish are resilient if given the minimum to survive.