replica DC

Dear Friends!
I would like to setup a Replica DC in another site. the current situation is as follows:
2 sites connected via VPN by cisco routers
Main site:
1, windows 2000 server as Main DC,DNS and dhcp(holder of all FSMO roles)(to be get rid off later)
2, windows 2003 server r2 replica DC,DNS and file server (all FSMO roles will be moved to after FSMO seizer for win2000,and dhcp)
3, Exch2003SP2
4, clients using 172.16.42.x network from dhcp

remote site:
only clients with 172.16.43.x network geting from dhcp router, the router allocates them the dns server in main site, this way they connect to dc and exchange.

before doing the seizer of 2000 server dc I would like to setup a replica dc in remote site and make it also a GC and setup a DFS for file server in main site and in remote site so replication is made and data is availabe to remote site also and vice versa.

my questions are
1- where should I setup the new dc replica for the remote site? in main site to make replication, specially if I'm going to replicate also the file server for the first time, the data is about 200 GB which is impossible to replicate from remote site,but this way how do I then change the IP addess when I move the server to the remote site, will this affect the DC function or not
2- should I create a new site and a subnet for the remote site DC replica in the AD sites and services, or not, if yes how can I do that?
3- in some readings I read that if the DC replica is in a remote site then the dns ip settings should point to itt self and not to the main site DNS IP, is this right?
how then the DNS servers will replicate whith each oher?

I hope that I'm not confusing someone , because my self I'm confused about these issues
please give some clue how to start

thanks a lot in advance

Jordi