Legal Question in Personal Injury in California

Depends on the situation. General civil cases, no. Statements can be taken, however, and they are likely required in your own insurance company's investigation (if applicable), otherwise voluntary. Uninsured/underinsured motorist cases may not ever have a lawsuit filed, but depositions can be taken.

They can be taken, but without court order they are not binding unless all parties agree and participate or waive participation.