[Samba] NIS / Samba

[kaze]

Can I take an existing bunch of local users accounts and flip it into a NIS
or Samba PDC server?

Can a Samba box serve the same directory data as _both_ a NIS server and a
Samba PDC?

Assuming an environment with a few servers with static DNS and IP info where
the clients are not doing any peer to peer file and print sharing, what is
the downside to NOT having an Active Directory, i.e. a Samba 3.0 PDC?