A. You can use the following command to display all users who have an EAS partnership established for the specified server:

Get-Mailbox -server -ResultSize:Unlimited |
ForEach \{Get-ActiveSyncDeviceStatistics -Mailbox:$_.Identity\} |
ft identity,devicemodel,LastSuccessSync

(You should type the previous command on one line in PowerShell.)

To view all EAS users for every server, simply remove the -server parameter.