[Samba] best road to go... Win2008R2 +samba4

[L.P.H. van Belle]

Hai..
 
Few questions, before i go start my project. 
 
i now have 2 domains,  samba3  with ldap ( DOMAIN1) ( and dns )   , and separated Win2008R2 (DOMAIN2)  ( and dns ) 
 
Since i dont have any lic's on my win2008 for users want to know if its possible to do the following. 
 
Keep the Win2008R2  also DHCP+DNS ( and i have some dns slaves  )  DOMAIN2 
Join Samba 4 to the DOMAIN2 , transfere the FSMO roles, so samba4 is the master DC of the domain. 
 
I cant touch the win2008 server, its my phone systems... 
is setup the following,  DNS is running bind.
Windows2008 DHCP+Master dns ( with 5 sub domains.. ) 
        => samba3 server, slave dns 
        => mailserver server, slave dns 
        => proxy server, slave dns. 
 
And my question is, can i run a setup like this. 
do i have to move my dhcp server to samba4, or can i keep it as is and only move the FSMO roles. 
 
next step is, move my current domain1 to domain 2. 
 
And if someone has a better setup to go with please tell me ;-) 
 
 
Best regards, 
 
Louis