I agree with Mr. Lassen that your friend should get a personal injury lawyer. Get one immediately, as there are deadlines for personal injury cases known as statutes of limitations, so retain a lawyer before time runs out.
It varies. Before working as a plaintiff attorney, I worked for years for a huge Philadelphia defense firm, and the firm might spend anywhere from 25-50k on average defending these cases, depending on the severity.
Sorry to hear about your assault. You may have a claim against the nightclub for inadequate security, thus, retain a local personal injury lawyer from Avvo in your city if you choose to pursue. All the best!