He is a guitarist but I don't think that he is that famous guitarist.
Guitarist = gitarist
No. The word guitarist's is a possessive noun (of or belonging to a guitarist). There is no adverb form.
yes guitarist is
Ray Toro is the lead guitarist, and Frank Iero is the other guitarist.
usually there is a vocalist, a bass guitarist, a drummer, a rhythm guitarist, and a lead guitarist
Hedley's guitarist is Dave Rosin.
Rise Against's current guitarist is Zach Blair, the guitarist before him was Chris Chasse.
Dan Lead Guitarist, Cooper Guitarist, Jameson Base Guitarist, John Drummer