I think learning something like FCS2 would be analogous to learning Photoshop, which I'll assume you've had some experience with. 🙂
It just takes a lot of playing around, a few glances at the manual and some Google searches. You'll become accustomed to what tools you have available through Final Cut, and you'll be fine.
The basic cutting is extremely simple. Once you have your footage imported, you just set an in-point at the beginning of the section you want to use, and an out-point at the end, and then drop it into your timeline, where you sequence all of the clips you've cut like that.
The rest, as mentioned above, is more of an art.
I think if it's something you want to do, you should definitely go for it. We'll always be here to answer your questions!
As for a good camera, there are so many out there, there's not a specific one to recommend. If you're thinking about doing these documentaries professionally, and for hire, you would most probably want an HD camera of some sort. The "prosumer" format of that is HDV. Professional places use better formats like DVCPRO HD or HDCAM, but those get extremely expensive. I guess I'll let other people talk about specific models.
As a photographer, I'm sure you're very informed about lenses, aperture, exposure, and ISO (which roughly translates to "gain" on video cameras... sort of). Unfortunately cameras with full manual controls over all those things and changeable lenses appear mostly in professional-grade equipment. So for a camera that you can use all your photographic knowledge on, it will be quite expensive.
I don't want to end on a low note so... kittens!