@Azuretech Thank you for this question. Please find below the response to your questions related to update management center:
- The difference between the methods available for update installation (scheduled or onetime) is based on the schedule of updates - they are both done by the "update management center" extension. This extension is automatically installed when you initiate any update management center operations such as check for updates, install one time update, periodic assessment on your machine and there is no manual intervention required for managing/installing this extension. Please see the details in this link (especially the description after the image). For managing updates on multiple machines, please see this link.
- Update management center (preview version as available now) does not support pre/post installation script as of now.
Please let me know if you have any question.