Nice quiz. "Ave Maria" is a bit tricky as Bach wrote the accompaniment (as a harpsichord piece) and Gounod added the tune over the top. Perhaps use another piece for Bach – e.g. Brandenburg Concertos or Toccata and Fugue in D minor?
Good quiz - apart from the Haydn question. There are probably thousands of composers who have written Trumpet concertos. Vivaldi, Torelli, Tartini, Bach, Telemann, Mozart, Maxwell-Davies..... Could I suggest that you change the clue to Die Schöpfung (The Creation)?