The Google Cloud Translation API cannot be currently used to directly translate files in PDF format. According to the API’s reference page the currently supported file formats include plain-text or HTML. Therefore, PDF files will need to be converted, by any suitable third-party services available online, to plain-text or HTML first before being translated via the Translation API.
Access to the Google Cloud Translation API Premium Edition is available to customers on a case-by-case basis and so it is not possible to give any timeframes on this matter. More information regarding this can be retrieve from the Premium Edition information page.
Since this form is processed by the the Google Translation API team you will have to wait until you get a reply from them.
Lastly, note that it is currently a Beta feature of the Google Cloud Translation API. This feature might be altered or changed in the future, and is not subject to any SLA or deprecation policy. This feature is not intended for real-time usage in critical applications.