A lawsuit is going to cost much more than the price of the ticket. Much more.

That is up to the parents of the 16 year old.

Unless the judge orders them not to, they can. Tell the DA or your victim's counsel who can take appropriate action.

I am sure some will. Call and ask. Many lawyers won't.

Unlikely unless he missed a filing deadline that cost you your case. Send him a letter respectfully requesting a sit down of Zoom meeting with him...

Duplicates of all those documents are easily attainable.

Try Google. I am not sure what you are asking.

Can they sue me? They are suing me. That answers the question. Now they have to prove their case.

Realistically, this is not a DIY project. The insurance companies will have lots of lawyers, and you need one as well.

Same answer as yesterday. Speak to your lawyer.