How do you get gap insurance on a used car?

I have been with my current insurance company for three years. How often are you supposed to change car insurance companies?

"Borrowing against my 401(k), I can cut my car loan interest rate in half and lower my payments by $100. This would extend the loan to 60 months, but I only have 36 left currently. Should I use this 401(k) loan to pay off my car balance?"

My car was parked in the street overnight and was hit by two other cars. Both insurance companies are refusing to fix my car. I don't have collision on my policy, so my insurance company won't help, either. The damage is around $5,000. Should I go to court?