Ok, I read the Odyssey like... 10 times so, I cant read the top question, but the answer the second one is,
He offers to pay him back with an alliance after he makes it home. The vow is important because Odysseus was arguably the most powerful ruler at the time. So, an alliance with him would help Alcinous a lot.
Because of the way he has been brought up, Walter Cunningham won't take any lunch money from Miss Caroline. As Scout explains in the book, Walter is a Cunningham, and in Maycomb, the Cunninghams are known to be a poor but proud family. I hope this helped!