Hello, Car insurance companies typically total a car when it costs more to repair it than what the car is worth. Since it has already been totaled, it's highly unlikely that a car insurance company would be willing to give you full coverage (comprehensive and collision) for a rebuilt title vehicle.
Most financing companies will require you to have comprehensive and collision coverage which means you would not be able to get storage insurance. Check with your finance company to see what options you have.
You should have no trouble getting mobile home insurance to cover your home including the add-ons, and there are several companies that will insure that type of home. You will need an HO-7 homeowners policy that specifically covers mobile homes.
This question is very specific to your homeowner's policy. Your agent will be able to tell you what type of coverage you have and the adjuster will be able to tell you how much they will pay to repair the damages. Usually, when there is custom work, it needs to be stated in your policy when it is written.