let me do my research real fast and I will let you know what I can find
1. The heart of the Happy Prince won't melt because it is full of kindness inside.
2. The people throw away the heart and the body of the swallow because they don't find them beautiful and useful anymore.
3. The angel chose the objects because these two things represent gratefulness.
4. The heart is a good symbol in the story because it shows that physical things does not really matter.
"Misery of Hunger, torture of thirst; unending discomfort of swarming lice."
the words from number 2 are intended to capture the reader's attention