Contact the party that issued the insurance policy for this answer.
They may raise your rates so I wouldn't tell them.
No, not unless you want to have repairs or need to repair another person's car. If you got a ticket because of the accident they will know because the ticket will be reported to them.
The world invalidate means not valid or to make invalid. Other such definitions include: to nullify something. One can use it in an example as follows: The court found enough evidence to invalidate the contract.
Try gathering enough proof and choose the right words, and declare why it was not your fault.
Ultimately, the decision to declare a vehicle a total loss belongs to the insurance company. If the insurance company is unable to have one of their own adjusters look at the vehicle, they will usually hire an independent. The repair shop can write an estimate and take pictures, but the insurance company will decide (based on state law and their own policies) whether or not the vehicle is a total loss.
In the UK, no, not usually, but you do need to declare them.
Yes.
can be done by insurance company at time it is totaled out by them
Sure, why not?
An insurance company declares a vehicle totaled when the cost to fix the vehicle exceeds 70% or more of its market value.
No, Insurance Company cannot increase premiums retroactive. It has to declare before hand from which date the increased rate of premium would be operational.
No.. but you should "declare" business use and mileage to your insurance carrier to avoid problems with a claim down the road.