Hi Steve,
In order for updates to your control to be seen in your VI, you need to save the control as either a type definition or a strict type definition. The creating custom controls link below explains what a type def is.
Creating Custom Controls, Indicators, and Type Definitions
https://zone.ni.com/reference/en-XX/help/371361H-01/lvconcepts/custom_cont_ind_type/
Using the LabVIEW Shared Variable
http://www.ni.com/white-paper/4679/en/
As far as your second question is concerned, can you be more specific as to what you mean? Could you post a screenshot of what you're trying to do, or what error you receive?
Thanks
Andrew B.
Application Engineer
National Instruments.
http://www.ni.com/support