Our current Scenario consists of the following;
DC server - running on Windows 2003 enterprise edition 32 bit . Holds FSMO and acts as GC server. Holds DNS & DHCP
ADC- running on Windows 2003 enterprise edition 32 bit. Not a GC and holds DNS.
Exchange 2003 with SP2 running on windows 2003 standard edition.
Clients-200 (windows XP 32 bit with SP3, Windows 7 Pro 32 bit with SP1)
Member servers-15 (windows 2003 enterprise editions 32 bit & 63 bit)
Now we are planning for transitioning our Domain from windows 2003 to windows 2008 R2. But we will not migrate our exchange 2003 to 2010 in the near future.
I have already started the test environment having 2 Dcs in windows 2003 and one exchange 2003 SP2. I have Already created a DC with windows 2008 R2 but not yet transferred the FSMO roles to the new dc but transferred the DHCP from the old windows 2003 dc to this new server. Now I have a few queries;
1.	 I have already raised the domain functional level to windows 2003 before making the windows 2008 R2 as dc. Should I also change the exchange operation mode too?
2.	 Should I prepare another additional domain with 2008 R2 before transferring the FSMO?
3.	What are the areas I have to take care when transferring the FSMO from windows 2003 to windows 2008 R2?
4.	Will my exchange 2003 SP2 work without any problems after completely transitioned from windows 2003 to windows 2008 R2, without raising both domain & forest functional level to windows 2008? (i.e. both functional level will be raised only to windows 2003).
5.	Will my users face any connectivity issues after the transition?
6.	Will my email users face any troubles after the change?
7.	Are there any good resources/books that can be of any help with my current transition?