Is there a tutorial showing the use of Google Maps widget in Thingworx Composer?
2. How can I display multiple markers - can I pass in an array for the "Data" field?
Some examples would be really useful.
I can answer the second question for you:
You can attach an infotable-generating service to the Data source on the Google Map, and then specify the LocationField to the corresponding infotable field containing location data.
As long as you have multiple rows being returned by the service/in the InfoTable provided as the Data Source, you should see multiple markers on your map, corresponding to each of your data rows.