Instead of being anonymouse, ask him to help you understand a tricky doctrine or some dishonesty in a recent magazine, maybe the two recent 607 Watchtowers.
They have to dig their own hole, throw themselves in it and drag themselves out. You can't do that for them by inundating them with info that you think is relevent. They are taught to not read anything from opposers, or talk to opposers. Material from apostate sources are the scariest for them.
Only work with Watchtower literature, anything that is quoted by that literature and anything you know they trust, like dictionaries etc.. Try to get him to supply the literature and information.
Their primary doctrine is that the WT was selected by Jesus in 1919 to be Jehovah's sole channel of communication. As long as they believe that, the WT has control over them. Every question you ask should chip away at some aspect of that doctrine, hence my suggestion of the 607 WTs.
Keep it to one question at a time to keep him focused. JWs thrive on distraction. Distracting you and themselves. Don't offer any, don't fall for any.
He is taught that he has a message that can save you from a killer god. Encourage him to save you. Ask all of your questions in a way that really makes him want to have a sensible answer for you.
Good luck
Chris
