Office 365 Business Premium - Join this device to Azure Active Directory

Hi - Looking for some advice\guidance on the following question.

We have a small business customer (5 x Windows 10 devices) currently in a 'workgroup' environment (no local server). They wish to migrate to Office 365 Business Premium. I've noticed in Windows 10 (settings - Accounts - Access work or school - +Connect) there is an option to 'join this device to Azure Active Directory'.

1) Is it possible to join Windows 10 devices to Azure Active Directory provided through Office 365 Business Premium?

2) Does it require Azure Active Directory Premium P1 or P2?

3) If it is possible, what are the benefits of joining.

4) Does it allow device management from within Azure AD?

5) Any further information (links to resources etc.) would be really appreciated as it will enable me to make the right decision going forward.

I look forward to hearing from you.

Regards