Your last email is pretty good. However, speaking from experience, I've found the best way to have any kind of discussion is to keep the topic narrow and focused. It's too easy for a JW to bounce from topic to topic, skimming the bare crown (because most of their knowledge is less than wading pool depth) and moving on. If you discuss one thing and one thing only and keep bringing your JW back to that topic, you might get somewhere (similar to the example of an earlier poster).
For example, I had a recent email exchange with a JW whose email covered about ten things that were supposedly evidences for creation. My response focused only on one of them and pushed her to look at it a bit more deeply (critically). It was a fool's errand, anyway(!)
Welcome, by the way.