Who started playing the piano at a very young age?
A (Joshua) - He states, "I started playing the piano when I was five years old..."
Who has a better social life now?
The text doesn't directly compare their current social lives. However, A (Joshua) mentions playing in a band with old college friends and playing at parties, suggesting an active social life connected to his music. B (Mary) mentions being part of a local orchestra and having friends who share her love for music. C (Peter) mentions playing in a band and teaching people, which also suggests social interaction. Based on the information given, it's difficult to definitively say who has a better social life.
Who didn't like playing the piano at first?
B (Mary) - She says, "Last year, I signed up for piano lessons. At first, I hated it! It was a lot of work and I practised the same songs over and over before I got them right."
Who plays the same instrument as family members?
C (Peter) - He says, "...My grandfather played the bagpipes, and so does my father, so I learned how to play when I was very young. Now, I teach people how to play the bagpipes as a part-time job." 
Who plays an instrument you don't usually hear about?
C (Peter) - He plays the bagpipes, which he describes as "a little more unusual."
Who plays music with friends they've known a long time?
A (Joshua) - He mentions playing in a band with his "old college friends."
Who tries to play better than other musicians?
B (Mary) - She mentions taking part in "international competitions against top piano players," indicating a competitive drive to play at a high level.