The correct spelling is "The Tell-Tale Heart," although you will find it spelled "The Tell-tale Heart" sometimes.
In the end of the story, "The Tell-Tale Heart", the narrator confesses to the murder because the beating heart drove him mad. The beating heart that he hears symbolizes the tale of guilt. The...
Yes.
Someone who killed another person
It tells you, it will reflect who you are inside. Or if you mean physcially, you cant - it operates by itself without influence from a conscious mind.