LM1200 PPPoE question

Hey all!

Current setup: I've got a modem which is where the internet comes in from. This is then connected to the WAN port via gigabit ethernet cable to a netgear router. On the internet connection settings page it uses PPPoE and I've supplied a username/password. This is needed to allow the internet to work.

1) My question is, once I plug in the LM1200, will the username and password for the PPPoE need to be plugged into the LM1200 or be kept on the router? If theres no facility on the LM1200 to input a PPPoE usernamd/password, does the LM1200 support a PPPoE passthrough of some sort so I can continue using the main broadband as is and use the cellular as a failover?

2) Once the failover mode is activated, will the LM1200 ignore the PPPoE settings (username/password) for my main connection?

TIA!