Generally speaking, the parent with primary custody should insure the child on their policy. The tricky part would be if your son will be driving your vehicle while at your home and his father's vehicle when he stays with him.
The state of Florida requires that you register a car within 10 days of starting a new job in the state or enrolling a child in school. Your insurance company doesn't care where the vehicle is registered because you have to get insurance before you can register it anyway, so that shouldn't be a problem.
The insurance company of the at-fault driver should be providing a replacement vehicle until your truck is repaired. You might even have coverage for a replacement on your existing commercial policy so it might be a good idea to contact your insurance provider to ask.
Animals cause all sorts of damage to vehicles, and not always because someone hits them with their car. Luckily, insurance companies don't discriminate over you hitting an animal or an animal hitting your car.
You won't need insurance for the title transfer, but you will when you register the vehicle in Minnesota. When it's time to purchase insurance, I always recommend comparing quotes with as many companies as possible to find the lowest rate.
If the truck is paid off and is only driven on your personal property, you are not required to insure it. The state will require that you register and insure it if you plan to put it on the road, but you won't need to until that point.
While it is correct that your home will need a separate policy for flood coverage, you do not need it for your auto insurance as long as you have comprehensive coverage. Comprehensive covers things like fire, theft, vandalism, and flooding.
Renters insurance is generally inexpensive, but splitting the bill may save a few dollars. Consider, however, that you will also be splitting the amount of coverage on the policy, so your personal items will both be covered at half the listed amount.
A credit score is a section of the overall "insurance score" that partially determines your insurance premium. The reason credit is used to determine rates in most states is due to the correlation between a driver's score and their likelihood to file a claim.
In a case where you are considered at-fault in an accident, in Virginia, your deductible should only apply if your vehicle was damaged and you want it repaired by your insurance company. The only other time you should be subject to a deductible in Virginia would be if you are filing an uninsured motorist property damage claim.