Answer to Question 1
If a defendant is able to demonstrate that the plaintiff knowingly put themselves into a situation where they were aware of the danger, and they chose to continue to be exposed to the danger, but there was a negligent act or defective equipment then as assumption of risk agreement might not be admissible during a negligence lawsuit.
Answer to Question 2
Tort lawsuits are instigated by individuals and criminal lawsuits are filed by states by a district attorney since they are crimes against the public.