Gerard,
I don't have a current folder structure to look at, or this model camcorder on-hand, but here are a couple of docs from Sony's website (which has got to be the most awful, convoluted site on the Internet):
Sony HDV Workflow with Final Cut Pro
HVR-MRC Memory Recording Unit Manual
The latter PDF file (for the MRC) is more detailed about the file structure.
These will get you started, at least.
By the way, just in case you need it... here is the plugin for FCP:
Sony Recording Unit RAD Plugin for FCP
-Dave
P.S. - Thanks again for posting the FAQ wiki article (H.264 in .mp4 files).