The format that iMovie uses to capture to is not a native format for FCP.
From what I'm understanding here, you would really do well to read through the first few chapters of the FCP manual. Especially the sections about setting up a project.
If the manuals are too hard to understand, there are plenty of other
resources out on the market to help beginners understand the basics of this program. Many of those resources have been written by the very users of this forum.
Also, do some searching in this forum for Canon related firewire issues. I've never used a Canon camera, so I'm no help there.