Hi,
To obtain the values of your controls in the subVIs, you'll need to wire the reference to your VI by an invoke node "Get Control Value [variant]". Then you can use "set control value" to pass the values to the next subVI.
Close button in your subVI will not remove it from the subpanel. You can try using the get control value property node to obtain the status of the stop button, and use subpanel's Remove VI invoke node to remove it from the subpanel.
You can start by checking the examples in the NI Example Finder. Look under Build User Interfaces/General/
simple.vi, templates.vi and viewer.vi
Hope this helps,
Dan