FROM THE BATTLEFIELDS of World War I to the glitz and glamour of 42nd Street, from gun-happy mobsters to disgruntled showgirls to arrogant divas, “Give My Regards to Broadway” has it all. Music by Irving Berlin and George M. Cohan make this a lively show. The children’s theater production opens at the Chautauqua Theater in downtown DeFuniak Springs on April 2 and runs through April 5.