MS Scheduler features and experience

Hi there - looking to implement MS Scheduler. There are a few questions I am struggling to find any information for online, I'd appreciate any extra insights:

1. Scheduler Metrics
   Is it possible to see in the admin portal, how many times Scheduler is used across the organisation, how many meetings are generated to understand what value is being delivered?
2. Delegated mailboxes
   Some of users delegate their mailboxes to an assistant. Does scheduler work with an assistant’s delegated access to another mailbox, or does it only interact with the person who has the licence?
3. External User Experience
   If an external person (outside company) is invited to a meeting, do they receive anything from Microsoft in addition to the Cortana emails?

Many thanks for your help!