Scott,
I’m in a hurry so I didn’t get to read your whole post, but I use the same camera and settings, here’s your first mistake:
In you FCP sequence, go to Sequence>settings and change the compressor to ProRes. You will have to render the timeline, but then you export with QT, NOT QT Conversion. Put that in compressor and choose 90 minute best quality, in DVDSP you will have to set your track to 16×9, but it will work great.
Have a wonderful day.