What is the piano lesson?
The lesson of the title is not about Maretha learning to play, or Berniece refusing to take on students. It is the lesson of the piano, taught to the Charles family. The piano signifies both the future and the past of the family, and they are taught to reconcile these sides of the piano, to not let one subjugate the other.
Who deserves the piano?
This is the main question of the play, and of course it's about more than the physical piano. The piano with Berniece is a history that is remembered but only stagnantly, not developing or growing. The piano with Boy Willie is history sold out in order to purchase a future. Wilson seems to think that the answer is in a mediation of these two extremes - keeping the piano, but allowing it to live and breathe.
What is the biblical symbolism of the struggle over the piano?
Boy Willie's assertion that he will cut the piano in half brings to mind the story of King Solomon and the disputed baby. By having Boy Willie echo the role of the undeserving mother in the biblical story, Wilson foreshadows that Boy Willie will not be the true guardian of the piano in the end.
Why can't Boy Willie and Lymon lift the piano the second time?
It could be because the ghost of Sutter has begun making his presence known in the physical world - and indeed, the ghost interferes more and more from that point till the end of the play. But it could also be because Lymon, having grown sympathetic to Berniece's point of view during their encounter the previous night, is beginning to doubt Boy Willie. And without Lymon's full will, that piano is not going anywhere.
What is the function of Grace's character?
Her scene with Boy Willie is a bit of comic relief, also serving to further characterize Boy Willie, and to build up to Lymon's more important scene with Berniece. But she serves an important expository function in the finale, when she is the only person able to express aloud the feeling shared by the whole Charles family - that of being in the presence of a ghost. She is an outsider, and the fact that she too feels the ghost serves to confirm for all involved that the ghost is real.
What is Sutter's claim to the piano?
Legally it is his, through and through. According to the laws at the time, he purchased the original piano in a fair trade; had right to the fruits of the labor of his woodworking slave; and could pass down the piano to his descendants. This is why, in order to obtain the family history inscribed on the piano, Doaker and Wining Boy had to steal it, and pay for it in yet more blood and tears. Sutter's claim is a legal one to the physical piano, but its soul belongs to the Charles family.
Why did Wining Boy stop playing the piano?
Wining Boy speaks of his life as a modern day minstrel, carrying an upright piano on his back from saloon to saloon, singing for his whiskey. He felt chained to this piano, seen only as a part of the instrument, a fixture, rather than as a person himself. So just as the piano symbolizes the chains of slavery for the entire family, so it was an even more literal set of chains for Wining Boy, weighing him down and impeding his progress in life.
Describe the role that Doaker plays.
Doaker is an intermediary and a neutral voice at the same time. He professes to take no side in the debate over the piano, yet refuses to allow Boy Willie to remove the instrument from his house. In the case of a stalemate in the argument between Boy Willie and Berniece - as is the case through most of the play - Doaker "sides" with Berniece by default in favoring the status quo. Nevertheless, he makes no effort to convince Boy Willie, and largely serves the narrative by being the rational voice that stops the events of the play from coming to a head before the first scene is complete.
Why doesn't Berniece marry Avery?
According to Berniece, she just isn't looking to get married. She makes a compelling feminist argument that she shouldn't be stripped of her womanhood just because she chooses not to have a man - an argument that is somewhat undermined by Wilson's pairing of Berniece's reluctance to remarry after the death of her husband with her unwillingness to push past the history of the piano. Bernice's singleness, like her attitude to the piano, is presented as a state to be overcome.
Why does Boy Willie want to buy Sutter's land in particular?
Boy Willie wants Sutter's land because it is the land that his family worked for generations before emancipation. Yet he speaks little of the specifics of the land he wants, and usually talks only generally about the benefits of land ownership. But in reality, he doesn't want just any land: he wants Sutter's, and it is because he is trying to honor and redeem his family's history, a similar goal to Berniece's, but pursued in a very different manner.