Box 1: 1 -
One single Azure AD tenant is needed as only the Corp tenant is migrated.
Box 2: 1 -
Box 3: 2 -
One conditional access policy for Multi-Factor Authentication (MFA) will be used for administative access, and a second conditional access policy in order to prevent external access.
Reference:
https://docs.microsoft.com/en-us/azure/active-directory/conditional-access/howto-conditional-access-policy-location
https://docs.microsoft.com/en-us/azure/active-directory/conditional-access/howto-conditional-access-policy-admin-mfa
