The law varies from state to state. You should consult with an attorney who specializes in probate in your area who can review your situation and determine what your options are.
Yes. They would inherit according to the laws of intestacy in the state where he lived. You can check the laws for that state at the related question below.
Many insurance companies offer a no claims protection service, which in my experience is worth having. It's not normally offered until you've built up 4 years NCB. If your NCB is NOT protected then a...