Untangle setup

Hi all,

I am currently setting up Untangle to use as a firewall in a school. I am probably being really simple but as I will be using it between the internal switch and router I would set it up as a transparent bridge is this correct?

Also would I give both the internal and external interfaces internal IP addresses or, just the internal and the external would get a 192.168 IP?

Sorry if these seem like daft questions.

Cheers