Ask them if they consider you to be one of Jehovah's Witnesses. If they say yes, ask why they waited so long to come around.
If they say no, ask them "what is the purpose of your visit?"
Ask why they never replied to your 50 questions.
Realize you won't reach them. They might be stumped and have to go ask for help on how to handle you, but you won't change them.
If they get around to asking you about the "faithful slave" and whether you believe it is God's channel today, a question one friend of ours asked is this: "Do you think its POSSIBLE that the WTS will ever change their view of the Faithful and Discreet Slave?" They should answer that it is possible, because it isn't an "etched in granite" doctrine. For example, they will never change their view of who God is, who Jesus is, are the dead really dead? Those are solid Bible teachings. The other things are all interpretation.
So, the point is, why should you be chastised or even disfellowshipped for questioning those kinds of teachings, that are subject to change?.............possibly.
If they answer, "no" that it will never change, you can either drop it, or use the information in the above paragraph about solid teachings and interpretations, and the difference.
Have fun and let us know how it goes.