Clarify usage of URL templates with callback preference

Section 8.2.8.2 introduces and describes the use of the 'callback' preference which must include a 'url' parameter. It also describes that the service can advertise it's support for the callback preference by means of the CallbackSupported annotation from our Capabilities vocabulary.

The CallbackSupported annotation, of CallbackType, represents the collection of protocols supported but also a UrlTemplate, a template which can include parameters, parameters for which the meaning can be documented in a document referenced by a DocumentationUrl.

The clarification I'm seeking is twofold:

1. What is the relationship between this UrlTemplate property in the CallbackSupported annotation and the url parameter specified as part of the Callback preference?
2. Can the requester specify a url template as part of that url parameter referencing variables that are available/advocated by the service using this template?

FYI: what I'm trying to do is to allow the requester to specify if, and if so how, it wants the job/request ID (an ID we assign to our asynchronous requests) passed to the service being notified of completion of such job.