Hi Kevin,
Don’t worry about the render files. Those are only generated when you build a timeline with effects that need to be rendered in order to play in real time. In fact, the only folder of the FCP folders that will fill up with a significant number of files will be Capture Scratch and, eventually, Autosave Vault. You can actually delete the Render Files folder to save disc space, but remember that any rendered effects will need to be re-rendered if you do.
As for the audio out of sync issue, I have the same problem in FCP 5.1.4. So far, the best I’ve been able to figure out is that the Sony HDV deck and camera are no longer supported by Apple. I am still working on this issue, since it brings my production department to a standstill. We are not currently able to capture HDV footage. It’s unacceptable. When I learn more, I will share it here.
Video Production Department
The Buddy Group
http://www.thebuddygroup.com