One of the fields in the return is the OperatorID, which is an integer. How does this number get chosen and does there exist some database where I could look up a number to determine network operator or owner that correlates to that ID?
IDs are automatically allocated when the item is added to our database and they are typically sequential.
See our API docs for how to retrieve our core reference data (lists of operators, connector types etc). https://openchargemap.org/site/develop/api#/operations/get-referencedata