Migrating from Exchange 2010 to Exchange 2013

Hello,



I am preparing to migrate from Windows 2008R2 & Exchange 2010SP2 to Windows 2012R2 with Exchange 2013.



Our single domain controller is running Windows 2003 SP2.

Domain functional level: Windows Server 2003

Forest functional level: Windows Server 2003



Is there a good link or document you could furnish so that I follow appropriate steps?



Also, some specific questions.
•Can I retain the Windows 2003 server for the time being?  Or does it need to be replaced with a Windows 2008 or higher DC first?
•Does Exchange need to have SP3 prior to being able to add Exchange 2013 on the network and migrate?

Thanks in advance.



Regards,

RealTimer