Hershey Felder, the pianist and actor who has embodied musicians such as George Gershwin and Ludwig van Beethoven in previous shows, is Fryderyk Chopin in his latest stage biography, Monsieur Chopin, directed by Joel Zwick. In the script he has written, Felder climbs into the skin of Chopin, and reveals both the highs and lows of the 19th-century Polish pianist-composer’s life and career.