some newbie questions, some implementation questions

[Andrew Kohlsmith <akohlsmith@benshaw.com>]

I have several questions regarding LDAP in general and have scoured the
FAQs, web, IRC... anywhere I could find.  These questions have not been
answered elsewhere to my knowledge.

I'm in the process of creating a company-wide LDAP database for all our
contacts, internal and external.  Right now there are approx. 2000 entries
in an Outlook Contacts database.

Now I've been able to convert that to an LDIF file, so the bare conversion
is done.  My main problem is that the dn for everything in that LDIF file is
different.  most entries are like this:

dn: cn=My Name      or
dn: mail=me@here.com cn=My Name

which won't be searchable with my base dn of o=organization, c=CA.

Do I just use sed and append on a "o=organiation, c=CA" to the end of the dn
of every entry?

second question: what's the advantage of using "dc=domain, dc=com" as
opposed to "o=organization, c=CA" ??  I see it but have not been able to
find what the advantage of using domain class is.

big question: is it possible to add fields to the database at a later date? 
i.e. let's say I have about 5000 to 6000 entries and suddenly need a
widgetclass field...  can I just add it in and the ones added from now on in
hav this field or do I have to start from scratch?

almost last question: is it possible to get ldapsearch or searches via
ldap://ldap.mydomain.com/searchquery to return *everything* in it's
database?  ldbmcat will do this, but how would I get a listing of everything
(in a client program, for instance?)

last question...  ldapsearch.  I have not been able to find decent
documentation on it anywhere!  sometimes it returns without saying anything,
other times it will tell me no object found... why the difference?

Please... if these questions have answers that are obvious, let me know
where to find the answers.  It seems that all the search engines return are
products but no information, or the openldap faq which has a lot of
information lacking for someone trying to get a decent grip on directories.

Thanks,
Andrew