I'd make sure you use the A/V in/outs and if you have to - use RCA to mini adapter to get into speakers. I use an old tuner that I can change from CD to AUX depending on if I am using the MAC sounds or the DECK sounds.
The whole VIEW menu thing...
Not sure I remember how it was in v3... but under the VIEW menu in FCP there was an option for EXTERNAL VIDEO... that should be set to ALL FRAMES and that will give you the video OUT via FW to the deck/camera. But there should be another option under there that asks where you want the audio to go... make sure it FOLLOWS VIDEO.
Might need to hunt for it.
CaptM