What documents can I sign for my personal injury case? Should I be signing anything?

Do not sign ANYTHING without a thorough review, preferably by a personal injury attorney. If you accept any kind of payment or reimbursement, or if you accept fault or responsibility for anything more than you should, that could have a detrimental effect on the outcome of your case. The insurance company is trying to pay the smallest amount possible to make a case go away. And they are going to do everything they can to make that happen. This may be the only time you have to deal with an insurance company, but they do this all the time. Do not underestimate their intentions.