When you join to independent clauses with a conjunction you stablishes the equality in this clauses, however in this case you can see that the clauses have a causal relation, it could be said If you don’t hold my hand, I will drown, in this case the best conjunction to put the clauses together is “or” “Hold my hand or I will drown.”
To provide possibly past events in the songs or to give information to the people watching or help to pass the time and make it a little fun and not so depressing when times are ruff. Kinda hard to explain it's more so of what your view of the songs and the scenario of which the song starts.
It seems they are asking how the dwarves and goblins being anger at Bilbo, and to compare them with the effects of Bilbo's choice in the book.
