Disguises and false identities abound in The Barber of Seville as men — young and old — vie for the hand of the beautiful Rosina in one of the funniest and most frenetic operas ever composed. Rossini’s delightful 19th-century romp centers on “Figaro, Figaro, Figaro,” a scheming barber and jack-of-all-trades, sung by Dallas Opera favorite Nathan Gunn, who plots with Count Almaviva to release Bartolo’s ward from her gilded cage.