Exchange 2003 – RPC over HTTP

Hi,
We already have Exchange 2003 server under cluster environment. We don't have front end exchanger server separately. Now the requirement is to segregate back and front end server from the existing environment.
Main purpose to configure front end exchange server is to configure RPC over HTTP proxy i. e. Outlook anywhere.
Now, my questions are:
1. What precautions need to be taken while installing/configuring front end server?
2. Do I need to change any settings in existing Exchange 2003 cluster mode server?
3. Do I need to make changes in our Active Directory services?
If anything else needs to be considered, then please include those points also.
Thanks.
