Gateway frache using dev. What types of interface to choose?

All kind time of day! Installed in a VirtualBox FreeBSD 9.1, I want to make it as the gateway.
The scheme is as follows:
ISP> home router -> em0-em1 -> network

In VirtualBox did two interfaces, what types of connections you need to choose?
I chose the network bridge on em1 and em0, the host machine pings as properly? I would appreciate your help by types of connections.

And which interface to choose as external (ем1 or em0)?

P. S. don't kick if something is wrong asked one night just for Rajoy sat %)