hand in hand is when two people are holding each others hands tight.
Yes. They make left and right handed guitars. They are strug backwards. They are correct for the "right" person.
The problem, pervasive in all aspects of the story, is poverty. Every Spirit demonstrates poverty to Scrooge, and once he has reformed, even Scrooge's generousity and open-handness emphasizes the poverty and need he was hoping to alleviate.