I think all of the possible tips and advice have already been covered and / or you've already done it. The only other thing I tohught of was sealing your flood barrier with expanding foam or bathroom sealant, when I lived in a flood area that's what people used to do)
I was flooded a few years ago, water up to 6 feet through our downstairs. I had moved things upstairs or onto our kitchen worktop but the water went well over that so, definitely go for upstairs for everything. If it gets to the point that water is going to come in, just let it come in. When we researched all the flood prevention stuff after our flood, the advice seemed to be not to go down the route of floodproof doors etc. because it could cause strutctural damage to the property if the pressure builds too much so, accept it's coming in once it gets to a certain point.
I would say definitely have a plan of somewhere to go and go there if you can, even if your house doesn't flood, if the whole area is flooded you could be out of power, water (so no toilet etc.) and unable to go out your front door and it's a miserable situation to be in. We were evacuated from our street but some people chose to stay and then got stuck, with no electric or heating, or access to food and it was absolutely miserable for them.
The water emptied our kitchen cupboards a bit, and tipped our bin over so there was the rubbish from our bin all over the place so might be worth bearing that in mind. Also your fridge, washing machine etc. could you put those up somewhere so they don't get ruined? Ours got lifted up and tipped over despite being in a tucked in spot under the worktop!
Drying out wise, we weren't insured so although obviously that was bad, a silver lining was that we could get straight in once the water subsided, and clear out. We were told remove anything that holds water and we got bags of sawdust free from our local timberyard which we put all over our floors (once carpet up) to soak up the mousiture, we then shovelled it all back up into bags and got rid.
Dehumidifiers - if you need them better to hire industrial ones from a local plant hire type place than a usual domestic one. We had 2 huge ones downstairs going constantly and had to drop in twice a day to empty them.
The water is dirty obviously because it will have whatever is in the drains etc. in it however, you don't have to throw away absolutely everything it has touched - stuff can be cleaned - we threw away things that in hindsight we should have cleaned and kept.
Most of all, best of luck, hope you don't need most of this advice and hope you're all ok xx