Yes
All of Chopin's works included the piano he did this because he was a pianist and a piano teacher
None. Everything involves the piano one way or another.
Chopin wrote secular music. All of it is for or at least involves his instrument, the piano. He wrote no sacred music at all.
Frederic Chopin wrote classical music and most of his music was composed for the piano. He was from Poland and considered one of the classical greats.
Chopin composed for the piano. His pieces include Preludes, Nocturnes, Waltzes, four Scherzos, Etudes and a Concerto.
Chopin was the composer who brought the piano one step higher. His compositions were highly deviated from the galant style. Among his compositions are: nocturnes, preludes, walzes, impromptus, mazurkas and polonaises.
He mainly made music for the piano and he did write some music for the flute. He also wrote music for the drums also and one more was the saxophone. I think that's how you spell it! :)
Chopin Few composers in the history of Western music have understood the intrinsic nature and potential of the piano as an expressive instrument as well as Chopin did
Piano,
Yes
Well, Beethoven wrote for the piano orchestrally. Schubert wrote for the piano vocally. But possibly the first person to write for the piano truly pianistically was Frederick Chopin. There have been many others, of course, but Chopin was the first really great composer to understand, in your words, the "nature and potential of the piano as an expressive instrument".
Chopin composed about 23 according to wikipedia, but some might have been lost, so 23 is probably the minimum