Here's my question:
I have over 250gb of footage in my current FCP project file, of which I may only use about 30-40gb in the project's sequence. The rest of the footage was never used (Documentary edit, hence the large amount of throw away footage)

I would like to backup the project onto an external hard drive, but I only want to backup the footage which was used in my sequences - I don't care about backing up the ~200gb extra. Is there any way to do this easily in FCP?

Also, for that footage which is backed up to the new hard drive, I would like FCP to provide a 10 second "buffer" before and after the footage (I.e. if the original clip is 60 seconds long, and in my sequence I use 20 seconds of footage, I would like final cut to store a total of 40 seconds of footage on my backup).

From what I understand. the media manager can be used to do the above tasks. Are there any tricks or anything I should know about using it?
Thanks

I just started learning FCP a little over a month ago so I'm probably not qualified to answer you but- I DO believe "Media Manager" will do this for you.

I even forget what menu it is accessed under but it will export an archived version of your project and even allow you to specify a length in "handles" for the footage you DO use so that you can go back and to minor tweaks on the timing of the edits/transitions.

Lastly, it also gives you a bar graph to signify the ORIGINAL size of the project and the NEW size after the unused footage is trimmed.

Check out Larry Jordan's article on the subject.
http://larryjordan.biz/articles/lj_media_mgr_delete.html

Here's my question:
I have over 250gb of footage in my current FCP project file, of which I may only use about 30-40gb in the project's sequence. The rest of the footage was never used (Documentary edit, hence the large amount of throw away footage)

I would like to backup the project onto an external hard drive, but I only want to backup the footage which was used in my sequences - I don't care about backing up the ~200gb extra. Is there any way to do this easily in FCP?

Also, for that footage which is backed up to the new hard drive, I would like FCP to provide a 10 second "buffer" before and after the footage (I.e. if the original clip is 60 seconds long, and in my sequence I use 20 seconds of footage, I would like final cut to store a total of 40 seconds of footage on my backup).

From what I understand. the media manager can be used to do the above tasks. Are there any tricks or anything I should know about using it?
Thanks

Everything you ask for is covered by the Media Manager. A trick? Launch the copied project to make sure the Media Manager actually copied everything. The last couple of times I used it, it did but in previous FCP versions some files were missed. Usually graphic files.