It would be good to know for sure about the vapor barrier. Wood doesn't like moisture, especially if the moisture/humidity levels under the house are high.
How old is the house and what part of the country to you live in?
How thick is the top layer of the plank?
How thick is the plank itself and how many plys?
Is the floor a single layer of OSB?
I'm kinda guessing that the glue is a good idea. There's a couple guys here that can help a lot better than I can............. I'm just fishin' for a bit more info to understand the project. That doesn't sound like cheap flooring..