He can question you if he wants but you have no obligation to answer him. The first thing you need to establish is whether you're free to leave. If not, do not answer any questions and request a lawyer.
Hire a personal injury lawyer right away, you can deal with your insurance on property damage if you have collision, but don't give any recorded statements, even to your own insurance, without your attorney present.
Even simple cases can take a long time to settle. Your friend's best bet would be to meet with her attorney to fully discuss her case. If necessary, she can fire her attorney and get a new one who will be more responsive.
I agree with attorney Doland. In addition, are you aware whether you ever purchased underinsured coverage through your own auto insurance. In some states, unless they can provide you with a signed underinsured rejection, you will be entitled to them. Check with a local attorney about what the delay in settlement is and ask him to check into any coverage through your own policy.
If your insurance company will provide you with a defense you probably will not need another lawyer. The time you would still need your own lawyer would be if your insurance company offered to pay out its limits and the Plaintiff refused to settle for that amount. That would be a rare occurrence unless you have substantial assets to go after.