Misc: What type of plant does Broom Hilda sell?

Questions

Mendelssohn's wedding march begins on an unusual chord of which type ?

When an independent Poland was carved out from Russian, German, and Austrian territory after WWI, this pianist became its first prime minister. ?

This Russian composer is known for his children's piano pieces. ?

Haydn was taken in by this noble patron in 1761 and remained in the service of his family for the next 30 years. ?

Richard Wagner's second wife Cosima was the illegitimatedaughter of what famous virtuoso ?