[Exim] configuration

Hi !
I have been successful in configuring exim on a standalone linux box Thanks to all of u for helping me out but now the real problem starts .To make it match the existing setup an upgrade the existing setup.
My query is .
MY SETUP.
We have sun netra m/c which has been loaded with Netscape enterprise server
2.0, Netscape proxy server 2.0 and Netscape mail server2.0 all running on
the single m/c .
The Problem is that i want to separate my mail server from the above setup.
We use the same domain name ( abcl.co.in) for all our purposes .
Now my plan is (i am not sure that if i can do it) i would like to separate
my mail server put it on a linux box and let the other two entrprise (web
site and proxy server) keep running on the sun netra solaris 2.5 .
What should my new linux server be like (configuration).Do i have to put
some separate entries in the sun m/c?I do have some static ip addresses free
with me?can i use them .I have read some where of Network Aliasing .can that be used.
Do i have to use a separate domain name .at present all my users have mail
id as abc@??? + ccmail users abc@??? + some more subdomains
whose gateway is also the same.
My query is if i set up a separate linux box with exim can i have the same
set up without changing the mailids if yes then how ?
I do not want to take risk of removing netscape mailserver from the sun
netra m/c bcos its live !!
What do u suggest how do i go about .?
I hope i am clear on my side .
Netscape has a userfriendly window based format for entering usernames and
adding users .How to add the users in exim?As i have some 300 users using
mails .Does one are create users in linux by adduser command shall that be
fine ?Or is it some thing else.
Where does the users mail get stored my spool dir is in /usr/exim /spool.?
My questions may be very wierd but i am determined to impliment exim by 1 st
jan 2001.
Thanks for your guidance

Neeraj Manral
Internet Group
2nd floor, ETD Building
Kanjur Marg
Mumbai - 400042