I would like to get all users from xchange server with EWS. I have figured out how to get all rooms and all appointments. But I specifically need all users thus I can CRUD users
On Exchange 2013 and above you can use the FindPeople operation with the GUID of the address list you want to access (eg for the Global Address List you use the GAL's guid).
You can then page the results back using the Offset
The one catch with this is you can't get the GUID you need using EWS you need to use the Get-GlobalAddressList cmdlet https://technet.microsoft.com/en-us/library/aa996579(v=exchg.160).aspx in Exchange Management Shell which will return the GUID you need for the request.
Cheers Glen