[Samba] Best way to upgrade domain from control by 2.2.5 PDC to control by 3.0.20b PDC

[Kevin]

Hi Folks-

I'll start by saying thanks to all the people who have made samba and
shared it as open source software.  Samba is truly an amazing suite of
software.

I have a small domain of less than 10 clients which is currently being
controlled with a Samba 2.2.5 PDC running on a Compaq x86 server with a
very old Suse Linux 8.1 OS.

Since setting up this Compaq server, my preferred distribution has
changed from Suse to Gentoo and my ultimate goal is to upgrade the OS on
the Compaq server to Gentoo.  Perhaps the biggest reason for the change
in preference is the difficulty I've found in upgrading any rpm-based
distribution.  Because I've tried it so many times and lost days or
weeks of time in the process, I don't think I even want to try a direct
upgrade of the samba-2.2.5-80 rpm on this Suse 8.1 OS, but I thought
that I would instead, install a new server on the network with the
Gentoo distribution and all of the latest software in Gentoo portage.
With that in place, I figured I would slowly migrate the services
currently being provided by the Compaq server to the new server.  Since
the PDC and other samba services are the most mission-critical
components of the network, the biggest step in the process seems like it
will be getting the new server set up to do all of the PDC and other
functions of the old Compaq server.  One important aspect of the
migration is that I'd ultimately like to end up using ldap as the
backend database.

It seems to me that there are at least two ways to go about performing
this migration step:

1) make the new server a PDC with the ldap backend; once running, and
all other services are unloaded onto the new server, take the Compaq
server offline and upgrade it to Gentoo, maybe making it a BDC (or not
using a BDC at all).

2) make the new server a BDC (not sure if I would have a choice in the
backend here) to the old PDC, then upgrade the old Compaq server from
Suse 8.1 to Gentoo, and restore it as the PDC for the domain after
upgrading the whole OS and samba to the latest release

My first question for the list is: which one of these methods is likely
to be least problematic and least time-consuming?

My other questions are:

a) Any problems with a samba-3.x BDC backing up a samba 2.2.5 PDC?

b) If I go with method 2 above, am I right in thinking that I'd have to
stay with the smbpasswd backend for the BDC (which is what the PDC
uses)?  This would only be a very temporary arrangement; I realize that
it's discouraged in the docs.  If not, and if ldap could be the backend
for the BDC somehow, then how would I accomplish this?

c) If I go with method 1 above (seems like it might be easier to me
right now), what are the key files that need to come over from the old
server to the new server?  I realize that the contents of (at least some
of, and maybe all of) these files would probably need to be revised
somehow (maybe putting them in the LDAP Directory), but what information
must be preserved from the old machine to make sure that I don't have to
go around to all of the clients and add them to a new domain?

d) I'd obviously like for it to be a seamless transition as far as the
clients go and the fact that the two servers will have different IP
addresses is a concern there.  And if I go with method 2, will the
clients need any reconfiguration to use the BDC for login (until the
Compaq server can be upgraded to Gentoo and be back in business as the PDC)?

e) Relating to the set of questions in (c), if I have an existing
openldap-v2.2.27 server running with a few LDAP Directories (with a
domain/contact sort of schema built from LDAP fields in existing schemas
like inetperson and courierimap and a few others) in it on a third
server, would it be possible to use one of the existing Directories as
the ldap backend authentication source for the new samba server or would
I need to create a new Directory with a "samba-only" schema to be the
ldap backend?

Thanks for any replies.

-Kevin