WAY BACK when, I seem to remember iMovie saving movie files as ".dv" files, which then needed to be rendered in Final Cut to be played back (because the audio was 44.1 kHz or something strange that iMovie did).
They've probably fixed this by now.
Still if you find yourself needing to render, something is probably wrong. If not, then you're not going to lose any quality from doing what you just told me.
To try getting the camera working in Final Cut, attach the camera, then
Go to Final Cut Pro-> A/V Settings
Under Device Control Preset, choose (probably either Firewire NTSC or HDV Firewire)
Close that window, then go to View->Refresh A/V Devices
Next, hit Command-8. See if it shows anything as being attached.