In paragraph 9, what the phrase "drew him on by artful questions" means is that he questioned him to try to gain privileged information.
He had to find out some information that was very important to him, so he started questioning him furtively so as to get to the bottom of things.
It allows the reader to see how the character came to be who he or she is currently, it creates realism in the text, it creates tension between the narrator and the character, etc.
It’s convincing someone to do or believe something
