Question : 2008 AD, MOSS with 2003 AD, MOSS

I am bundling several questions as I think most of them have a common theme.

All the servers I have are 32Bit Win2K3 Ent R2 servers which includes Active Directory, MOSS 2007, SQL Server 2005. I am currently considering Win2K8 64 bit editions and the questions I have to do with integration with the current environment. I guess there could be manuals out there which decribe it in great detail, but I am looking for users experience and also links
to concise articles if possible.

(1) I have 2 AD servers on individual Win2k3 32 bit machines. If I want to bring in another AD server on Win2K8 64 bit machine, what are some of the considerations?

(2) I have a sharepoint farm which currently consists of a App server and DB (SQL 2005) on Win2k3 32 bit machines. I want to bring in another front end server for load balancing and another DB server into the farm.
      (a) Should I bring in the front end as a WFE or as a application server?
      (b) Is it okay to install MOSS 2007 SP1 on a farm which was originally installed as a just MOSS 2007 and never upgraded to SP1.
      (c) Is it okay to have this server on Win2K8 64 bit machine?
      (d) Is it okay to bring in a SQL Server 2008 on a Win2K8 64 bit machine into the farm which currently has SQL server 2005 on Win2K3 32 bit machines.

Please advice. All help will be truly appreciated.
Thanks.

Answer : 2008 AD, MOSS with 2003 AD, MOSS

(1) You can have both x86 and x64 Active Directories running in your infrastructure
      You can have both Win2003 and Win2008 AD servers in yout infrastrcture
      There are differences between infrastructure levels of AD in win2003 and Win2008. If your level is 2003 you will not benefit of new features provided in Win2008 level.
      Take into concideration that in terms of platform management it is easier to manage homogeneous platforms, easier to install, manage and troubleshoot.

(2a) minimum service would be Web Front End, but concider also adding Search service, as this service would also get Load balanced as Web searches are services by Web Front ends. Typical topology woiuld load off Applications on a specific Server but it depends on your needs, see this artcile for greater details on points to take into concideration : http://technet.microsoft.com/en-us/library/cc262936.aspx
(2b) all servers in a Farm should be running the same level of patching SP and hotfixes, otherwise you will have problems running certain feature of the product. If you want to add to your farm a server running SP1 you must first upgrade all other servers with SP1.
(2c) SharePoint runs fine under Win2008 x64 beware though that having different platforms in a farm is not a good practice in terms of exploitation procedures. Although it would be running OK, in the same line it is good practice to have identical hardware and software for Web Front Ends running Load balancing.
(2d) Sorry but I do not see any gains? You would have a gain in terms of platform redundancy in building a SQL Cluster but they would have to be running identical hardware and software.