You could go to the district attorney's office and file a drop slip, however, it is still in the ADA's hands to whether they will drop the charges...

This all depends on what he stole, generally theft is a misdemeanor, but what upgrades it to a felony is the value of what was actually taken.

Should I hire an attorney

You should hire an attorney who handles personal injury, also you should see a doctor to start treating any possible injuries.

Most jurisdictions differ but most jurisdictions just let you pay everything to the probation officer and he will see take the necessary measures...

Will I be able to plea guilty with circumstances in court for a traffic ticket? Will the judge ask for the circumstances?

When you go to court you will only be able to plea guilty or not guilty. If you want to let the judge know about the circumstances on what caused...