Transfer Exchange Server between 02 Site

Dear All,
I'm newbies in manage and control Exchange Server so I hope that get more support from all of you. Thank you.
Below is all my issues,
Requirements:
      Transfer Exchange server system from SITE 1 to SITE 2.
My Planning:
At SITE 2:
      Step 1: Build 02 NEW AD and Exchange Server as well base on IP and Local Domain name. Mean, It could send/receive internal and external as well.
      Step 2: Go to Public DNS control panel, indicate the DNS re-point to IP WAN of SITE 2
      Step 3:  I’m stacked in thinking with existed user mailbox,
            (1) How to synchronize/process with User mailbox between 02 SITE ? MUST I re-create all User mailbox ? If so, I will busy job. Current, We had have around 200 User mailbox.
                (2) For User mailbox store who is keep on Server, How to restore it to new Exchange server ?
At SITE 1:
      Shutdown 02 the Server once all things at SITE 2 ready to transfer.