How to review Office 365 reports?

As most of you already notice that Office 365 today is very popular service as mail server and other online services, as we were used always to read exchange report so it is also important to introduce the  office 365 reports, mailbox service, we can go over to One Drive report, Active and inactive mailboxes, Role Group changes ,Share Point and more useful reports.
Some people claim the office 365 is the next IT world, and meantime it seems that there are rights, many organization transferred to Office 365 and preferred be there instead of maintaining the on-premise environment.
How to review Office 365 reports?
On Office 365 console select on report

Here we can see One drive report- Storage.

mailboxes are  active and inactive mailboxes:
new and deleted mailboxes
* Type of Mailbox connections which means OWA,MAPI,EAS,POP3,etc..
So useful report,
Mailbox usage and licensing vs Active Usage

Who changes? deleted?modified?

Full audit: