The Question and Answer section for Narrative of the Life of Frederick Douglass is a great resource to ask questions, find answers, and discuss the novel.
Douglas knew that the only way to overcome and defeat slavery was through education. Reading and writing was the best way to rise past the bondage of slavery. Knowing more than their masters was a potent weapond.
I'm pretty sure he was free by the end of the text.
Whisper means exactly that.... rumors or facts that must be kept secret. As for the second part of your question, this refers to the fact that slave children, no matter who their father happens to be, continue as slaves.