How important is it for your GC to be licensed and insured?

[Nick Brubaker]

Today is my last day of due diligence on my first flip property.  My real estate agent referred me to an experienced GC.  I like him and am confident he is reliable enough and would do good work, but I found out today that he is not licensed (previous license expired) or insured.  Also, some of his subcontractors are not residing here legally.  Is this an obvious no go on this contractor?  If so, do others here (I'm in Atlanta) have good GC's they can recommend?  I am also wondering if I could have a lawyer draft a waiver to eliminate any of my liability for accidents and what not on the job.