#Networking questions

Im reorganizing my network and I could use some help on the implementation. I have a basic design of what I want to achieve here: http://i1250.photobucket.com/albums/hh522/saskiller/redesign.png

Now in order to learn more effectively, i'm breaking this down into steps, which I want to keep in this thread. As I come up with questions/issues, i'll post them, hopefully get some answers and feedback/advice and learn something!

So first project is the router. In this setup it is intended to be a bridge, carrying the internet connection to the network.

Now issues I am having configuring the router:

1. I have installed a WIC-4ESW for ethernet connectivity to the internal network. In total that gives the device 1 external eth interface, and 1 (to be used in this setup) internal interface. Now according to my knowledge of networking, the external eth0 needs to be configured and connected, with the Wan IP possibly? The device will not let me enter interface configuration mode on eth0 saying it is an external interface.

2. Then I have vlan1 and FastEth0. My understanding that in order for the device to be managed remotely, vlan1 (management vlan) would need an ip address, and in order for pc's on the internal networks to be able to reach it, the devices need to be on the same network. However, If I attempt to assign vlan1 192.168.1.2 and fa0 192.168.1.3 SM 255.0, the device tells me they overlap. Where is my misunderstanding here?

3. I know I do not want this router performing DHCP/DNS/NAT (the firewall will perform those if possible) Is there any configuration on this router needed to insure I can do this? currently the modem is acting as the DHCP/DNS/NAT device, but I will change that later.