Yes, I highly recommend that you have legal counsel before seeking reinstatement of your license. You don't want to start providing documents and answering questions that will remain in your permanent Secretary of State file until you have consulted with an attorney. I recently wrote a blog post about this, which I will link to below.
Yes, you should hire a lawyer - the process is complex and denial rates are high. Your other questions are too difficult to answer without more information. You must consult an attorney who concentrates in administrative hearings before the Illinois Secretary of State to review your record, discuss specifics, and then quote you a fee. Many of us offer free consultations. More specific information on the Secretary of State hearing process is available at the links provided below.
The information contained in this answer is offered for informational purposes only. This information does not constitute legal advice, attorney advertising, or establish an attorney-client relationship. Individuals with questions in any area of the law should consult a qualified attorney licensed to practice in that individual's jurisdiction.